TOBRUK, Libya — Libya's opposition battled to keep Moammar Gadhafi's forces at the gateway to rebel-held territory on Thursday, hoping for help from the U.N. Security Council before his tanks and troops break through the city of Ajdabiya.
Gadhafi's rapid advance on the rebels appears to have spurred the United States to leave behind weeks of doubts about a no-fly zone in Libya, and start pushing for broader U.N. authorization for international air, sea and land forces.
The U.S. wants the Security Council to approve planes, troops or ships to stop attacks by Gadhafi on the rebels, according to a diplomat familiar with closed-door negotiations Wednesday.
The Obama administration said it would not not act without Security Council authorization, did not want to put U.S. ground troops into Libya, and insists on broad international participation, especially by Arab states, the diplomat said.
The U.S. and other supporters of action against Gadhafi were pushing for a Thursday vote on a draft resolution. Russia and China have expressed doubts about the U.N. and other outside powers getting involved.
By Thursday afternoon, Gadhafi's army had surrounded Ajdabiya on three sides, leaving open only the road north to the larger rebel stronghold of Benghazi.
Charred vehicles, bullet-riddled pickup trucks and an overturned tank littered the desert highway where pro-Gadhafi forces had fought up to the entrance of Ajdabiya, a city of 140,000. An Associated Press Television News cameraman counted at least three bodies by the side of the road, evidence of fierce battles. Government troops were bringing in a stream of truckloads of ammunition, rockets and supplies.
A rebel spokesman told The Associated Press that Benghazi, 100 miles (160 kilometers) to the north along the Mediterranean coast, was "armed to the teeth" and the opposition is ready to defend it.
A Benghazi resident who did not want to be identified for fear of reprisals said the city's young men were volunteering to undergo basic military training. Those already trained were seeking more preparation to be battle ready.
More checkpoints were popping up at intersections and on main roads, manned by men in uniform armed with Ak-47s and backed by anti-aircraft guns mounted on pickup trucks.
Mustafa Gheriani said by telephone from Benghazi that the opposition was hoping for a positive U.N. Security Council vote but "if not, we'll rely on ourselves and do what we can."
"Short of the genocide of east Libya there's little Gadhafi can do because he can't rule us anymore," Gheriani said.
A resident told the AP that Ajdabiya had been hit by hours of airstrikes but it was not clear if the government or rebels, who say they have at least three planes, are carrying them out.
"Gadhafi troops have not invaded the city on foot until now," said Moataz al-Ghariani, who lives in downtown Ajdabiya and is in touch with the rebels. "They are only imposing a siege from three fronts: the western, the southern and the eastern. No one can leave and no one can enter."
He said the rebels were surrounding a unit of Gadhafi forces at the eastern gates of the city.
Michael reported from Cairo. Anita Snow and Edith M. Lederer at the United Nations contributed.