U.N. inspectors in Syria suspect chemical weapons used in five areas

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A wounded Syrian woman walks with her children after airstrikes on a rebel area of the war-torn northern city of Aleppo. (Mohammed al-Khatieb / AFP/ Getty Images)

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Mourners attend a funeral for men killed during battles with members of the Al Qaeda-linked Islamic State of Iraq and Syria in the northern Syrian city of Aleppo. (Mahmud Al-Halabi / AFP/ Getty Images)

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Rebel fighters carry a man’s body at the Aleppo headquarters of the Islamic State of Iraq and Syria after he was allegedly killed by the AlQaeda-linked group in January. (Medo Halab / AFP/ Getty Images)

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A Syrian man helps an injured resident following an airstrike in Aleppo’s Maadi neighborhood. (Mohammed al-Khatieb / AFP/ Getty Images)

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A Syrian man reacts after an airstrike by government forces on the city of Aleppo. (Mohammed al-Khatieb / AFP/ Getty Images)

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Rebel fighters inside a building during clashes with pro-government forces in the Sheikh al-Said neighborhood of Syria’s northern city of Aleppo. (Medo Halab / AFP/ Getty Images)

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An opposition fighter runs through a hole in a wall to avoid sniper fire by regime forces during clashes in Syria’s northern city of Aleppo. (KARAM AL-MASRI / AFP/Getty Images)

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Opposition fighters open fire from behind a car during fighting in the Salaheddin district of the northern Syrian city of Aleppo. The Syrian Observatory for Human Rights reported fierce fighting in Damascus province between rebels and troops backed by pro-regime militias and fighters from Lebanon’s Shiite Muslim movement Hezbollah. (KARAM AL-MASRI / AFP/Getty Images)

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A Syrian rebel aims his weapon during clashes with government forces in the streets near Aleppo international airport in northern Syria. (Stephen J. Boitano / AFP/ Getty Images)

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Rebel fighters duck as they run behind a barricade to avoid being fired at by Syrian government forces in the Old City of Aleppo. (JM Lopez / AFP/ Getty Images)

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A fighter allied with Syrian President Bashar Assad runs across the street after fighting with rebels in the Yarmouk refugee camp in the capital, Damascus. (Anwar Amro / AFP/ Getty Images)

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A fighter of the Popular Front for the Liberation of Palestine General Command, allied with Syrian President Bashar Assad, jumps through the window of a destroyed building in the Yarmouk refugee camp in Damascus. (Anwar Amro / AFP/ Getty Images)

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An opposition fighter runs in front of a sniper curtain in the industrial area of Syria’s eastern town of Deir Ezzor during clashes with government forces. (Abo Shuja / AFP/ Getty Images)

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Free Syrian Army fighters clean their weapons and check ammunition at their base on the outskirts of Aleppo, Syria. (Khalil Hamra / Associated Press)

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Syrian government forces patrol the Khaldiyeh district of Syria’s central city of Homs. The Syrian government announced on July 29 the capture of Khaldiyeh, a key rebel district in Homs. (Joseph Eid / AFP/Getty Images)

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A Syrian national flag is waved in Damascus to show support for President Bashar Assad. (Louai Beshara / AFP/Getty Images)

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A rebel fighter takes aim at regime forces in the northern Syrian city of Aleppo. (Louai Abo Al-Jod / AFP/Getty Images)

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A man stands near destroyed buildings after reported airstrikes by Syrian government forces in the rebel-held northwestern Syrian province of Idlib. (Abu Amar Al-Taftanaz / AFP/Getty Images)

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Mustafa Abu Bekir, 23, second from left, meets relatives after crossing the Turkish Cilvegozu gate border. Abu Bekir said he was severely wounded by a bomb dropped from a Syrian army warplane while fighting with the Free Syrian Army in Idlib. (Gregorio Borgia / Associated Press)

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A man carries a boy who was severely wounded during heavy fighting between Syrian rebels and troops last year in Idlib. (Rodrigo Abd / Associated Press)

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Syrian President Bashar Assad arrives at a dinner event in Damascus on the last week of the Muslim holy month of Ramadan. (Virginie Nguyen Hoang / AFP/Getty Images)

By Patrick J. McDonnell

Dec. 12, 2013 8:56 PM PT

BEIRUT — A United Nations report released Thursday concluded that chemical weapons probably were deployed on several occasions in Syria, the most convincing evidence coming from the Aug. 21 attacks outside Damascus that left hundreds dead.

Chemical weapons may have been deployed in five of seven cases investigated, occurring between March and August, including the Aug. 21 incident, according to the report. The five locations were Ghouta, Khan Assal, Jobar, Saraqeb and Ashrafiah Sahnaya.

As expected, the 82-page report did not apportion blame for any of the alleged chemical weapons strikes. U.N. guidelines limited the investigators’ scope to determining whether chemical weapons had been used, not who may have deployed toxic arms.

Without a definitive conclusion, the report seems likely to extend the debate about who has used chemical weapons in the Syrian civil war, now in its third year.

Forces loyal to President Bashar Assad and fighters from the opposition have accused each other of deploying poison gas. The allegations are among the most incendiary in a sectarian-fueled conflict marked by frequent reports of massacres and other atrocities.

Various international experts and governments have cited evidence pointing to Syrian forces or the opposition in alleged chemical attacks, but no definitive proof has emerged.

The deadliest and most sensational incident was the series of attacks Aug. 21 in the so-called eastern Ghouta area, which was largely under rebel control. The incident appeared to be the only case in which U.N. investigators — who were in Damascus at the time — succeeded in identifying the likely source of the contamination: surface-to-surface rockets apparently containing payloads of sarin, a deadly nerve agent.

The U.N. investigation “collected clear and convincing evidence that chemical weapons were used against civilians, including children, on a relatively large scale in the Ghouta area,” the report said. The finding backed a conclusion reached in a preliminary U.N. finding in September.

Debates have raged in scientific circles and on the Internet about almost every detail of the Aug. 21 attacks, news of which was quickly broadcast worldwide via video of the victims. Some observers have since questioned the authenticity of the videos and whether some images were staged.

Others have questioned whether the sarin found at the scene of the attacks matched that in Syrian military stocks or was a homemade variant that could have been produced by opposition forces. Similar disputes have swirled around the kind of rocket allegedly used in the attacks and whether the payloads were launched from government-controlled or rebel-held areas.

The U.S. government has maintained that evidence strongly points to Syrian forces as the perpetrators. U.S. officials say more than 1,400 people were killed; other estimates put the number of dead in the hundreds. According to the Obama administration, only the Syrian government had the technical and logistical capability to carry out the strikes.

But an article by Seymour Hersh, a Pulitzer prize-winning investigative journalist, published Sunday in the London Review of Books suggested that U.S. authorities were aware that an Al Qaeda-linked rebel faction, Al Nusrah Front, was capable of producing sarin. U.S. intelligence officials subsequently denied suppressing any evidence about who may have been responsible for the poison gas strikes.

The Aug. 21 attacks eventually led to a U.S.-Russian pact that resulted in the Syrian government agreeing to relinquish its chemical weapons stockpiles under international supervision by mid-2014. The accord averted threatened U.S. airstrikes against the government.

Assad has denied that his military was behind the Aug. 21 attacks and blamed antigovernment rebels seeking to frame Syrian authorities and spur international outrage and U.S.-led intervention against his forces. Opposition representatives also denied being behind those attacks.

The U.N. team concluded that chemical weapons may have been used in four other incidents. However, in each of the four cases, the U.N. experts said, the attacks could not be independently verified because of a lack of reliable samples and an absence of “primary information” on how the chemical weapons may have been delivered. Security concerns prevented the U.N. investigators from visiting most of the sites.

The U.N. team compiling the report was led by Ake Sellstrom, a Swedish scientist.

patrick.mcdonnell@latimes.com