Libyan rebels have deployed tanks, artillery and a helicopter for the first time to repel an attack by pro-Gaddafi forces on the key town of Ajdabiya, the BBC understands.

Libyan rebels have deployed tanks, artillery and a helicopter for the first time to repel an attack by pro-Gaddafi forces on the key town of Ajdabiya, the BBC understands.

The town is the last population centre before the rebel headquarters in Benghazi - Libya's second city, with a population of one million.

Col Gaddafi's forces say they have taken Ajdabiya and Benghazi is next.

Earlier, the US urged the UN to act in Libya, including a no-fly zone.

US ambassador to the UN Susan Rice said a no-fly zone would bring only limited help. She hoped for an early vote on a draft.

Russia expressed concern at some of the implications of the proposals and put forward a counter-resolution.

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