20 Killed in Gaza Offensive

Israeli troops backed by tanks and helicopter gunships battled militants in the southern Gaza Strip on Tuesday, continuing the biggest offensive there during more than 3 1/2 years of conflict. At least 20 Palestinians were reported dead and 40 wounded in the daylong fighting.

Israeli officials said the incursion was an attempt to confront militants and staunch weapons smuggling along Gaza’s border with Egypt. That area has seen frequent, though smaller-scale, fighting between Palestinian gunmen and Israeli soldiers.

Israeli officials say cross-border tunnels to the Rafah refugee camp near where the battle took place are a pipeline for explosives and weapons destined for militants in Gaza.

Palestinian leaders charged that the raid, in the Tel Sultan neighborhood outside the camp, could trigger a humanitarian crisis. They appealed to the international community for help.

“What is going on in Rafah is a series of inhumane crimes and criminal acts against Palestinian civilians and their property,” Palestinian Authority Prime Minister Ahmed Korei said in a statement.

In defending Tuesday’s strike, the Israeli army’s chief of staff, Lt. Gen. Moshe Yaalon, said past incursions had failed to stem the flow of rocket-propelled grenades and launchers. Israel also could face a more serious threat posed by longer-range rockets, he said.

“After we tried to convince the Palestinian authorities to put an end to this, we have recently been forced to stop this ourselves,” Yaalon told reporters. “Those who prefer the smuggling of weapons over the lives of the population along the Israel-Egypt border are the Palestinians, and therefore we are forced to take the actions we are presently taking.”

Israeli officials said the incursion was not linked to the killings of 13 Israeli soldiers last week by militants in the Gaza Strip. There were no Israeli casualties reported in the latest fighting.

The assault began with a flurry of air attacks and skirmishes that killed 10 Palestinians in the predawn hours.

Tuesday, Israeli troops supported by tanks and aircraft formed a tight cordon around the Rafah camp and a neighboring town of the same name.

The ring in effect sealed off the southern tip of the Gaza Strip.

Palestinian ambulance crews reported that fighting made it harder to get to the wounded, and Physicians for Human Rights said the road closures kept medics from moving people to a better-equipped hospital in the nearby town of Khan Yunis. Israeli military officials said that they were trying to allow ambulances to pass but that sporadic shooting was causing delays.

The army said most of the casualties were gunmen. One Palestinian reportedly was killed while handling explosives.

The dead also included 14-year-old Asmaa Moghayer and her 11-year-old brother, Ahmed, who were shot after climbing onto the roof of their home to collect laundry.

On Monday, hundreds of Palestinian families fled their homes, fearing an Israeli attack and destruction of houses along a patrol road next to the Egyptian border.

Israeli forces demolished dozens of houses there last week, and officials suggested more might be razed to widen a buffer zone. On Tuesday, the nation’s Supreme Court for the second time in less than a week rejected an appeal by Palestinian residents to block such action. The demolitions have drawn international criticism, including from the United States.

Few houses were demolished during Tuesday’s raid, and Israeli military officials took pains to say the purpose was not to raze homes, except those used by gunmen or that concealed tunnel openings.

The incursion -- coupled with fears that more demolitions would follow -- prompted an outcry from the Palestinians and others.

Korei, the prime minister, urged the United States and the three other co-sponsors of a stalled Mideast peace plan -- Russia, the European Union and the United Nations -- to pressure Israel to stop the offensive. The Arab League called for a meeting of the U.N. Security Council to take up the matter.

Also Tuesday, Amnesty International issued a report accusing Israel of violating international standards on human rights by destroying more than 3,000 Palestinian houses and other property during the last 3 1/2 years, costing tens of thousands of people their homes or livelihoods.

Israel defended its right to raze houses where Palestinian gunmen take up fighting positions in populated areas or where homes conceal tunnels.

“When terrorists fire from within civilian structures or activate roadside charges from trees and fields, military necessity dictates the demolition of these locations,” the Foreign Ministry said. “Under international law, these structures are considered legitimate military targets.”

Times special correspondent Fayed abu Shammalah in Gaza City contributed to this report.