US President Barack Obama has defended the first military intervention of his presidency, insisting US involvement in Libya will be limited. He told Americans US participation in the coalition had saved "countless lives" threatened by the forces of the "tyrant" Muammar Gaddafi. But having led the initial campaign, the US would hand over to Nato allies on Wednesday, he said. Meanwhile, the rebel advance inside Libya has been slowed down near Sirte. While Nato insists it is impartial in the conflict, Russia has renewed its expressions of concern, saying intervention in an internal civil war is not sanctioned by UN Security Council Resolution 1973. Some 40 delegations - from the coalition, the UN, Nato, the African Union and Arab League - are preparing to meet in London on Tuesday to discuss the way forward for Libya. 'Regime change' ruled out "Tonight, I can report that we have stopped Gaddafi's deadly advance," Mr Obama said, speaking from the National Defense University in Washington DC. But the lead in enforcing the no-fly zone "and protecting civilians on the ground" would now move to US "allies and partners". "Because of this transition to a broader, Nato-based coalition, the risk and cost of this operation - to our military, and to American taxpayers - will be reduced significantly," Mr Obama said. "We must always measure our interests against the need for action," the president continued. "But that cannot be an argument for never acting on behalf of what's right... "We were faced with the prospect of violence on a horrific scale. We had a unique ability to stop that violence: an international mandate for action, a broad coalition prepared to join us, the support of Arab countries and a plea for help from the Libyan people themselves." He said that to broaden the aims of the military mission in Libya to overthrowing Col Gaddafi would be a mistake. The US, he said, had gone down that road in Iraq and could not afford the cost in lives, time and money again Earlier on Monday, Mr Obama spoke by video conference with French President Nicolas Sarkozy, German Chancellor Angela Merkel and UK Prime Minister David Cameron as part of his regular consultations with European allies. The leaders agreed that Col Gaddafi "had lost any legitimacy to rule and should leave power, and that the Libyan people should have the political space to determine their own future", a White House statement said. Advance slows Anti-Gaddafi rebels have seized a number of coastal communities and important oil installations in recent days, including Ras Lanuf, Brega, Uqayla and Bin Jawad. However, repeated attacks by government troops have prevented them reaching Sirte, a symbolic target for the rebels as the birthplace of Col Gaddafi. Bombardments of the road between Bin Jawad and Nawfaliyah reportedly sent the rebels fleeing back towards Bin Jawad. Nato has denied its air strikes are meant to provide cover for a rebel advance. Sir Emyr Jones Parry, a former British ambassador to Nato and the UN, dismissed concerns voiced by Russia as "puritanical". "Fundamentally, you're protecting civilians and to do that, you've got to get at the sources of the attack and make sure that they are negated," he told the BBC. Credit: BBC