TRIPOLI // Muammar Qaddafi's better armed and organised troops reversed the westward charge of Libyan rebels as world powers met in London on Tuesday to plot the country's future without the "brother leader".
Before the conference, President Barack Obama told Americans in a televised address that US forces would not get bogged down trying to topple Colonel Qaddafi, but he stopped short of spelling out how the military campaign in Libya would end.
The United States is scaling back to a "supporting role" to let Nato take full command from US forces on Wednesday, but air strikes by US, French and British planes remain key to smashing Colonel Qaddafi's armour and facilitating rebel advances.
It took five days of allied air strikes to pulverise Libyan government tanks around the town of Ajdabiyah before Colonel Qaddafi's troops fled and the rebels rushed in and began their 300-km, two-day dash across the desert to within 80 km (50 miles) of the Qaddafi loyalist stronghold of Sirte.
But the rebel pick-up truck cavalcade was first ambushed, then outflanked by Colonel Qaddafi's troops. The advance stopped and government forces retook the small town of Nawfaliyah, 120 km (75 miles) east of Sirte.
"The Qaddafi guys hit us with Grads [rockets] and they came round our flanks," Ashraf Mohammed, a 28-year-old rebel wearing a bandolier of bullets, told a Reuters reporter at the front.
The sporadic thud of heavy weapons could be heard as dozens of civilian cars sped eastwards away from the fight.
One man stopped his car to berate the rebels. "Get yourselves up there and stop posing for pictures," he shouted, but met little response.
Later, a hail of machinegun and rocket fire hit rebel positions. As the onslaught began, rebels lept behind sand dunes to fire back but gave up after a few minutes, jumped into their pick-up trucks and sped off back down the road to the town of Bin Jawad. Shells landed near the road as they retreated.
Without air strikes it appears the rebels are not able to hold ground or make advances. The battle around Sirte, Gaddafi's birthplace, will show if the rebels have reached their limit.
Reports that some Nawfaliyah residents had fought alongside government troops are an ominous sign for world powers hoping for a swift end to Col Qaddafi's 41-year rule.
Mr Obama said he had no choice but to act to avoid "violence on a horrific scale" against the Libyan people.
Qaddafi accused Western powers of massacres of Libyan civilians in alliance with rebels he said were al Qa'eda members.
"Stop your brutal and unjust attack on our country … Hundreds of Libyans are being killed because of this bombardment. Massacres are being mercilessly committed against the Libyan people," he said in a letter to world leaders carried by Libya's official news agency.
"We are a people united behind the leadership of the revolution, facing the terrorism of al Qa'eda on the one hand and on the other hand terrorism by Nato, which now directly supports al Qa'eda," he said.
The rebels deny any al Qaeda links and on Tuesday promised free and fair elections if Col Qaddafi is forced from power.
More than 40 governments and international organisations met in London on Tuesday to set up a steering group, including Arab states, to provide political guidance for the response to the war and coordinate long-term support to Libya.
Both Britain and Italy suggested Gaddafi might be allowed to go into exile to bring a quick end to the six-week civil war, but the US ambassador to the United Nations, Susan Rice, said there was no evidence the Libyan leader was prepared to leave.
The US secretary of state, Hillary Clinton, met the opposition Libyan National Council envoy, Mahmoud Jebril, before the London talks. A senior US official said the two could discuss releasing $33 billion in frozen Libyan assets to the opposition.
Such meetings also help Washington better understand the rebel leadership, its military forces and the problems they face, the official said, though Mr Obama pledged once again that US ground forces would not be deployed to help them out.
"We will deny the regime arms, cut off its supply of cash, assist the opposition and work with other nations to hasten the day when Qaddafi leaves power," Mr Obama said, but the United States would not use force to topple him, as it had in the 2003 US-led invasion of Iraq.
"To be blunt, we went down that road in Iraq," Mr Obama said.
The United States though has not ruled out arming the rebels, Ms Rice said.
"Over the long term, as the president said, there are other things that are at our disposal that perhaps will assist in speeding Gaddafi's exit," she told CBS television.
In western Libya, rebels and forces loyal to Col Qaddafi both claimed control over parts of Misrata and fighting appeared to persist in the fiercely contested city, Libya's third largest.
Col Qaddafi's forces launched another attempt to seize control of Misrata on Tuesday, said a rebel spokesman in the city which has been under siege for more than a month.
Government troops "tried an hour ago to get into the town through the eastern gate. The youths are trying to push them back. Fighting is still taking place now. Random bombardment is continuing," the spokesman, called Sami, told Reuters by telephone from the city. "Eight civilians were killed and several others wounded last night."
Another rebel spokesman, in Benghazi, said 124 civilians had been killed in the past nine days of fighting in Misrata, based on numbers obtained from hospitals in the city.