Libyan rebels were Friday battling Muammar Gaddafi's forces around the oil town of Brega, as the West backed off from arming the rag-tag fighters and pushed for a political solution instead.
An AFP correspondent citing rebel commanders said fighting had erupted around Brega, about 800 kilometres (500 miles) east of Tripoli Friday morning.
Rebels prevented reporters and civilians from leaving the strategic town of Ajdabiya for Brega, about 80 kilometres to the west, but it was unclear exactly where the frontline was or who controlled the refinery town.
The rebels had the previous day been beaten back by heavy shelling from Gaddafi's forces when they launched a counter-offensive at Brega in a bid to resume their march on Tripoli started soon after the uprising against the hardliner's rule was launched on February 15.
Rebel commanders called for air strikes by coalition forces enforcing a UN-mandated no-fly zone over Libya but the US military's top officer said bad weather was hampering the air campaign.
"The biggest problem the last three or four days has been weather," Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told senators in Washington, as correspondents at the front reported light cloud cover.
"We have not been able to see through the weather or get through the weather to be able to do this kind of identification" of targets, Mullen said.
Without air support, the ill-equipped rebels were on Wednesday pushed back 200 kilometres from the key oil hub Ras Lanuf all the way east of Brega, where they regrouped on Thursday for the counter-offensive.
As the rebels called for heavy armaments to match the superior firepower of Gaddafi's army, US Defence Secretary Robert Gates asserted they needed training more than guns but suggested other nations do that job.
His French counterpart Gerard Longuet said providing weapons was not part of the UN mandate while NATO chief Anders Fogh Rasmussen too ruled out such a move.
"We are there to protect the Libyan people, not to arm people," Rasmussen told reporters.
Grilled by US lawmakers, Gates described the rebels as a "disparate," improvised force that had a supply of small arms seized at regime depots but sorely lacked military leadership.
"What they really need is training, command and control and some coherent organisation," the Pentagon chief told the House Armed Services Committee in Washington.
He said the military mission did not call for deposing Gaddafi and suggested ultimately it would be economic and political pressure and Libya's people -- not coalition air strikes -- that would topple him.
Germany's foreign minister too said the situation in Libya could not be solved through "military means" and called for a ceasefire, almost two weeks into a NATO-led air campaign against Gaddafi's forces.
Guido Westerwelle made the comments after meeting his Chinese counterpart Yang Jiechi in Beijing on Friday.
"There can only be a political resolution and we must get the political process underway. That should begin with a ceasefire that Gaddafi must heed to allow the peace process to begin," Westerwelle told reporters.
The day after the regime was rocked by the defection of foreign minister Mussa Kussa, a report said British officials held confidential discussions in London with Mohammed Ismail, a top aide to Gaddafi's son Seif Al-Islam.
Citing a British government source, the Guardian newspaper said the meeting, one of a number between the two nations in the past two weeks, is believed to have addressed an exit strategy for Gaddafi and his regime.
Britain's Foreign Office refused to comment on the report other than to say it would not provide a "running commentary" on contact between the two countries.
The defections were read in the West as a sign the Gaddafi regime was beginning to crumble under pressure. But militarily, Gaddafi's forces showed they can still deliver blows to the rebels.
Mullen said about 20 to 25 percent of Gaddafi's military had been knocked out by NATO-led bombing but "that does not mean he's about to break from a military standpoint."
US, British, French, Canadian, Danish and Belgian jets have attacked Gaddafi's ground forces since March 19 under UN Security Council resolution 1973, which authorised "all necessary measures" to protect civilians.
As battles raged in the east, there was house-by-house fighting in the bombed-out streets of central Misrata, Libya's third largest city 132 miles (214 kilometres) east of Tripoli, which has held out against a relentless siege by Gaddafi's forces.
"Gaddafi is killing us," shouted one opposition fighter in a ragged uniform and a blue beret, as artillery fire blasted nearby. Tank and rocket explosions echoed around the shuttered shops, the homes and mosques of the city centre.
On the humanitarian front, UN High Commissioner for Refugees Antonio Guterres said it was "absolutely essential that humanitarian access is given to all those in need of assistance wherever they might be in Libya."
French aid group Action Against Hunger (ACF) said a new wave of refugees fleeing the fighting in Libya was crossing into Tunisia and warned even more might be on their way.
"A month after the start of the conflict, the number of displaced people fleeing the violence is again on the increase at the border between Libya and Tunisia," ACF said.
"Today 9,000 people are living in the camp at Choucha," compared with hardly 3,000 last week, the organisation said.
Wednesday's defection of Kussa, the most senior figure to jump ship since the uprising against Gaddafi's iron-fisted 41-year rule erupted more than six weeks ago, was widely seen as a sign of a crumbling regime.
British Foreign Secretary William Hague insisted Kussa, who has been linked to atrocities including the 1988 Lockerbie bombing over Scotland, had not been offered immunity from prosecution.
Scottish prosecutors said they had requested an interview with Kussa over the Lockerbie bombing, while Hague told reporters he was being interviewed "voluntarily" by British officials.