Tripoli, Libya -- NATO refused to apologize Friday for a deadly airstrike it conceded may have mistakenly killed people it has pledged to protect, angering Libyan opposition leaders amid an increasingly frustrating campaign to oust Moammar Gadhafi.
Gadhafi's forces attacked Ajdabiya on Friday with a barrage of artillery fire at the city's western gates. Ajdabiya has changed hands several times already, and rebels were forced to flee again in a war that is now viewed in some circles as unwinnable for the opposition, even with NATO air support.
NATO, meanwhile, was on the defensive Friday after reports of casualties apparently caused by the airstrike. British Royal Navy Rear Adm. Russell Harding said NATO forces may have hit rebel tanks near the eastern oil town of al-Brega on Thursday.
Witnesses told CNN that two rebel fighters and two doctors were killed when missiles struck a rebel formation on the eastern Libyan battlefront.
It was the second time NATO has been blamed for civilian deaths -- last week, opposition leaders said NATO airstrikes killed 13 civilians in the al-Brega area. NATO is investigating that strike as well.
"I'm not apologizing," Harding, the deputy commander of the NATO operation, said of the latest incident. "The situation on the ground is fluid, and we had no information the opposition forces were using tanks."
Harding said NATO had only recently learned that opposition forces had tanks. In the past, it was Gadhafi's tanks that had taken aim at civilians, he said.
"There's a lot of vehicles going back and forth," he said. "It is very difficult to distinguish who is operating the vehicles."
The airstrikes also injured 14 people, and an additional six are missing, said Gen. Abdul Fattah Yunis, a commander of the rebel forces.
NATO Secretary General Anders Fogh Rasmussen called the incident unfortunate.
"I strongly regret the loss of life," he said.
"We are conducting operations in Libya in accordance with the U.N. Security Council resolution with the aim to protect civilians," he said. "This is also the reason why our aircraft target military equipment that could be used to attack civilians, but I can assure you that we do our utmost to avoid civilian casualties."
Sorrow quickly turned to anger at a hospital where the wounded were taken, complicating matters for opposition fighters, already demoralized by the superior firepower of the Libyan army.
"NATO, NATO, NATO! They shouldn't hit the revolutionaries. We're helpless," one person screamed.
Ahmed Abu Bakr, a doctor who came to Libya from Germany to volunteer, said he never thought that he would be treating the wounded from friendly fire.
"I am very unhappy," he said. "They came here to help us, not injure us."
After the aerial attack Thursday morning, Gadhafi's troops pushed back the rebels, retaking territory and moving the front line farther east, Yunis said.
He said the rebels notified NATO of their tank movement and of their presence.
"There is no tension between us and NATO; this is a war situation, and we understand that mistakes are made," Yunis said.
Harding said Friday he did not feel NATO needed to strengthen communications with rebels.
"I have to be frank, it's not for us to improve communications. We have to see where civilians are being attacked and see if we can take action," Harding said.
A few hours after the strikes, civilians and rebels, fearing an approach by Gadhafi's forces, retreated from Ajdabiya, with hundreds of civilian cars and trucks loaded with rocket launchers and ammunition headed out of town in the direction of the opposition headquarters in Benghazi.
On Friday, Ajdabiya, only 100 miles from the rebel stronghold of Beghazi, was a ghost town. And as the battle raged with no decisive victories, some wondered if the outgunned rebel forces could prevail and if NATO has the correct strategy to help.
U.S. Gen. Carter Ham, who led the Libya mission before NATO took control, told lawmakers in Washington that the likelihood of rebel forces marching to Tripoli and ousting Gadhafi by military force -- even with NATO air power -- was "low."
Former CIA operative Robert Baer said NATO will have to put boots on the ground.
"First of all, the no-fly zone is not working," Baer told CNN. "Not a surprise to me that NATO bombed the rebel force. We sort of got one foot in this, but not completely. The logic of this conflict is you have to put people on the ground."
The United States ratcheted up pressure Friday on Gadhafi financially by extending sanctions to five senior Libyan government officials and two entities controlled by Gadhafi's children.
The sanctions bar business transactions with those on the list and freeze their assets that fall under U.S. jurisdiction.
On the diplomatic front, a former U.S. lawmaker who has been trying to meet with Gadhafi told CNN's "The Situation Room" that Friday would be his last opportunity.
Curt Weldon has said he will tell the strongman to step aside and take other measures to end the bloodshed.
A former Republican U.S. House member from suburban Philadelphia, Weldon has been to Libya before in his work as a congressman. He said he came to the country this time with "a small private delegation."
Weldon said he has met with other Libyan officials, including the prime minister and Gadhafi's son Saadi, conveying the Obama administration's stance on the crisis and reinforcing the importance of an immediate cease-fire monitored by the United Nations to protect civilians.
"I'm here only because I want to avoid war," Weldon told CNN. "I don't want to see American soldiers killed, and I don't want to see more innocent Libyans killed."
Meanwhile, the World Food Program said one of its humanitarian ships loaded with food, medical supplies and doctors has reached the besieged city of Misrata, providing what it called a "lifeline" for trapped civilians.Copyright © 2014, Los Angeles Times