By Mark Hosenball and Alexander Dziadosz
WASHINGTON/AJDABIYAH, Libya (Reuters) - As Libyan rebels fled in headlong retreat from the superior arms and tactics of Muammar Gaddafi's troops on Wednesday, U.S. officials said President Barack Obama had signed a secret order authorizing covert support for the rebels.
While the United States, France and Britain have raised the possibility of arming the rebels, they have all stressed that no decision had yet been taken.
As Gadaffi's army pushed back the rebels, their lack of heavy weapons and feeble fighting capabilities exposed the vulnerability of their forces in the absence of Western air strikes to tip the scales in their favor.
Despite some dissent within the Western military coalition attacking Gadaffi's forces, news that Obama had given the covert authorization surfaced as he and other U.S. and allied officials began speaking openly about the possibility of sending arms to the rebels.
Obama signed the order, known as a presidential "finding," within the last two or three weeks, according to four U.S. government sources familiar with the matter.
Such findings are a principal form of presidential directive used to authorize secret operations by the Central Intelligence Agency. This is a necessary legal step before such action can take place but does not mean that it will.
The CIA and the White House declined to comment.
It took more than five days of allied bombardment to destroy Libyan government tanks and artillery in the strategic town of Ajdabiyah before rebels rushed in and chased Gaddafi's troops 300 km (200 miles) west in a two-day dash along the coast.
Two days later the rebels have been pushed back to close to where they started.
While Gaddafi's forces were on the offensive the international face of his government, foreign minister Moussa Koussa, suddenly arrived in London on Wednesday to seek refuge after quitting the government in protest against the attacks by Gaddafi's forces on civilians.
"Koussa is one of the most senior figures in Gaddafi's government and his role was to represent the regime internationally -- something that he is no longer willing to do," a British government spokesman said.
The Libyan army first ambushed the chaotic caravan of volunteers and supporters outside Gaddafi's hometown of Sirte, then outflanked them through the desert, a maneuver requiring the sort of discipline the rag-tag rebels lack.
The towns of Nawfaliyah, Bin Jawad and Ras Lanuf fell in quick succession to the lightning government counter-strike.
Rebel spokesman Colonel Ahmad Bani said fighting was going on at Brega, the next town east along the narrow coastal strip that has been the theater of most of the fighting. But many rebels had pulled back further to the strategic town of Ajdabiyah and regrouped.
"We thought it better to make a tactical withdrawal until we can think of better tactics and a strategy to face this force," said Bani, adding: "One of the defense points will be Ajdabiyah, not the only one."
He appealed for more allied air strikes and heavier weapons. "We are seeking weapons that will be able to destroy the heavy weapons they are using against us such as tanks and artillery."
In Washington, U.S. Secretary of State Hillary Clinton said the Obama administration had made no decision yet on whether to arm the Libyan rebels and some lawmakers questioned the wisdom of such a move.
The chairman of the House of Representatives intelligence committee, Republican Mike Rogers, said he opposed supplying arms to the Libyan rebels "at this time."
"We need to understand more about the opposition before I would support passing out guns and advanced weapons to them," Rogers said in a statement.
In town after town along the Libyan coast, Gaddafi force's have unleashed a bombardment from tanks, artillery and truck-launched Grad rockets which has forced rebels to flee.
"These are our weapons," said rebel fighter Mohammed, pointing to his assault rifle. "We can't fight Grads with them."
Without Western air strikes, the rebels seem unable to make advances or hold their positions against Gaddafi's armor. Western airplanes flew over the battlefield on Wednesday, but there was no evidence of any bombardment of government forces.
Rebel forces lack training, discipline and leadership. There are many different groups of volunteers and decisions are often made only after heated arguments.
"Whether we advance 50 km (30 miles), or retreat 50 km ... it's a big country. They will go back the next day," rebel spokesman Mustafa Gheriani told reporters in the opposition stronghold of Benghazi.
"This revolution really is only five weeks old. On the political front it is very organized," he said. "Normally it takes six months to train a soldier ... We are talking about citizens who picked up guns to protect their homes."
Libya's official Jana news agency said air strikes by forces of "the crusader colonial aggression" hit residential areas in the town of Garyan, about 100 km (60 miles) south of Tripoli, on Tuesday. It said several civilian buildings were destroyed and some people wounded.
U.N. Security Council Resolution 1973 sanctions air power to protect Libyan civilians, not to provide close air support to rebel forces. That would also require troops on the ground to guide in the bombs. Without forward air controllers, intervening from the air in such a fluid battle space is fraught with risks.
Russia has already accused the allies of overstepping their U.N. remit by carrying out strikes on Gaddafi's ground forces and on Wednesday warned the West against arming the rebels.
Russian Foreign Minister Sergei Lavrov said it was obvious Libya was "ripe for reforms," but Libyans themselves must decide without influence from outside.
"I find it hard to see how the coalition can agree politically to arming the rebels, but without arms I can't see how the rebels can win," said Daniel Keohane of the Institute for Security Studies in Washington.
Aid agencies are increasingly worried about a lack of food and medicines, especially in towns such as Misrata where a siege by Gaddafi's forces deprives them of access.
But a blockade of Misrata's Mediterranean port by pro-Gaddafi forces has now ended, allowing two ships to deliver humanitarian aid and evacuate people wounded in the fighting.
Oil shipments from Africa's third-largest producer have been blocked for weeks due to heavy fighting and western sanctions. A source at Qatar Petroleum said it was struggling to work out how to market Libyan oil on behalf of the rebels.
(Additional reporting by Adrian Croft, Maria Golovnina, Angus MacSwan, Edmund Blair, Ibon Villelabeitia, Lamine Chikhi, Hamid Ould Ahmed, Marie-Louise Gumuchian. Writing by Andrew Roche and Christopher Wilson. Editing by Jackie Frank)