The fall of the eastern gateway urban centre followed a week of coalition action against Colonel Muammar Gaddafi's military, which included missile strikes by RAF Tornados yesterday and on Thursday.
The rebel victory in Ajdabiya dealt a blow to the regime, which acknowledged that the air strikes had forced its troops to withdraw and accused international forces of choosing sides in the fight.
"This is the objective of the coalition now. It is not to protect civilians because now they are directly fighting against the armed forces," deputy foreign minister Khaled Kaim said in Tripoli. "They are trying to push the country to the brink of a civil war."
His claims came as the Ministry of Defence released details of the mission carried out by British Tornado GR4 aircraft yesterday afternoon, which saw them take part in a co-ordinated missile strike against units of Gaddafi's military.
Major General John Lorimer said: "The Tornado aircraft launched a number of guided Brimstone missiles, destroying three armoured vehicles in Misrata and two further armoured vehicles in Ajdabiya.
"Brimstone is a high precision, low collateral damage weapon optimised against demanding and mobile targets.
"Britain and her international partners remain engaged in operations to support United Nations Security Resolution 1973, to enforce the established no-fly zone and are contributing to the Nato arms embargo of Libya."
Today's recapturing of Ajdabiya by anti-government fighters marked the first major turnaround for the uprising.
On the road into Ajdabiya, at least eight blackened regime tanks lay on the ground, while drivers honked horns in celebration and flew the tricolour rebel flag.
Others in the city fired their guns into the air and danced on the burned out combat vehicles.
Saif Sadawi, a 20-year-old rebel fighter, said the city's eastern gate fell late last night and the western gate fell at dawn after air strikes on both locations.
"All of Ajdabiya is free," he said.
Another rebel fighter, Ahmed Faraj, 38, from Ajdabiya, added: "Without the planes we couldn't have done this. Gaddafi's weapons are at a different level than ours. "With the help of the planes we are going to push onward to Tripoli, God willing."
The US commander in charge of the overall international mission, Army General Carter Ham, said the international partners could easily destroy all the regime forces in Ajdabiya, but the city itself would be destroyed in the process.
"We'd be killing the very people that we're charged with protecting," he said.
Instead, the focus was on disrupting the communications and supply lines that allow Gaddafi's forces to keep fighting in Ajdabiya and other urban areas like Misrata, he said.
But despite the air strikes and today's turnaround in Ajdabiya, forces loyal to Gaddafi remain a real threat to civilians, according to Pentagon officials in the US, who are considering expanding the firepower and airborne surveillance systems in the military campaign.
Ajdabiya's original fall to the dictator's troops prompted the UN resolution authorising international action in the north African country.
The operation has led to fears in Britain that Gaddafi could take revenge for the country's involvement in air attacks if he remains in power.
Justice Secretary Kenneth Clarke warned that the dictator could retaliate by staging another Lockerbie-style terror attack.
He told The Guardian: "We do have one particular interest in the Maghreb (the western region of North Africa), which is Lockerbie.
"The British people have reason to remember the curse of Gaddafi - Gaddafi back in power, the old Gaddafi looking for revenge. We have a real interest in preventing that."
Meanwhile David Cameron spoke by telephone today to UN Secretary General Ban Ki Moon and Qatari Prime Minister Hamed bin Jassem, who both confirmed they would be attending the international conference on Libya in London on Tuesday.
Downing Street said Mr Cameron welcomed the Qatari air force's first flight in support of the no-fly zone as a clear signal of the Arab world's commitment to enforcing UN Security Council resolutions.
The UN Security Council authorised the operation to protect Libyan civilians after Gaddafi launched attacks against anti-government protesters who demanded he step down after 42 years in power.
The air strikes have sapped the strength of the regime's forces but rebel advances have foundered and the two sides have been at stalemate in key cities.
Ajdabiya, the gateway to the opposition's eastern stronghold, and the western city of Misrata have especially suffered because the rebels lack the heavy weapons to lift Gaddafi's siege.
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