Rebels have spent the day locked in artillery duels with Muammar Gaddafi's forces in eastern Libya, as Western aircraft again struck at heavy armour used by the government in the region.

Opposition forces massing for an attack on the strategically important town of Ajdabiyah fired steady bursts of artillery at Libya army positions since this morning.

According to Reuters' reporters in the region, the rebels on the road to Ajdabiyah have appeared more organised in recent days, after initial disarray stirred doubts about their ability to pose a challenge to Gaddafi.

Western jets pounded targets in southern Libya yesterday but failed to prevent government tanks re-entering the western city of Misrata, whose main hospital was besieged by armour and government snipers.

It was hoped that rebel forces in eastern Libya would overthrow Gaddafi with the aid of NATO air support, but the return of tanks to Misrata under cover of darkness highlighted the difficulties they face in trying to force the Libyan leader to cease fire.

A rebel spokesman said that Gaddafi troops had shelled an area on the outskirts of the city, killing six people including three children.

The African Union says it is planning to facilitate talks to help end war in the oil producing country. But NATO says its no fly zone operation could last three months.

NATO members have agreed to enforce the no-fly zone over Libya, but will not take full command of all military operations in the country.

Differences over the scope the UN resolution gave for military action against Gaddafi's army led to days of heated arguments within NATO about its role in the operation.

Rebels, who have set up an alternative government in their eastern stronghold in Benghazi, say they need more ammunition and anti-tank weapons if they are to end Gaddafi's 41-year rule.

‘We need arms and ammunition. This is our only problem,’ rebel military spokesman Colonel Ahmed Bani told a briefing.

France, Britain and the US have led enforcement of the Libya no-fly zone imposed last week by the UN Security Council, which authorised ‘all necessary measures’ to protect Libyan civilians against Gaddafi's forces.

British Tornado aircraft launched missiles overnight at Libyan military vehicles which were threatening civilians in the eastern frontline town of Ajdabiyah, 150km west of Benghazi, the Ministry of Defence said on Friday.

Agreement on operation

A UK government spokesman said NATO's decision ‘to assume command and control of the no-fly zone, in addition to the arms embargo already being enforced, is a significant step forward.’

The UAE's decision to contribute 12 planes to the operation was evidence of the ‘real and tangible’ Arab role, he added.

NATO officials said a decision was expected on Sunday on whether to broaden the mandate to allow it to take command of all military operations and attack ground targets in the oil-producing country, in order to protect civilian areas threatened by Gaddafi's forces.

Earlier, Turkish Foreign Minister Ahmet Davutoglu told reporters: ‘The operation will be transferred completely to NATO and there will be a single command and control.’

The US, embroiled in Iraq and Afghanistan, is keen to step back and play a supporting role in Libya, preserve alliance unity and maintain the support of Muslim countries for the UN-mandated intervention.

US Secretary of State Hillary Clinton said military planners had been authorised to take on the ‘broader civilian protection mission’ and NATO was well suited to do so.

The number of US aircraft flying missions had dropped significantly as other nations increased their role, she said.

UN Secretary General Ban Ki-moon told the Security Council there was no evidence Tripoli was complying with UN resolutions.

His special envoy to Libya had warned Gaddafi's government of possible 'additional measures' if Libya failed to comply with its ceasefire demand.