British Prime Minister David Cameron has cut short his holiday in Cornwall to return to London, and chaired a Libya meeting on Monday as Libyan rebels pushed into Tripoli after months of stalemate in their conflicts with the government forces, local media reported on Monday.
The Prime Minister said there was "no room for complacency" in Libya.
British Minister for the Middle East and North Africa Alistair Burt, in the meantime, said the Libyan people should be given "a chance to choose their own government.
"We've always been clear that Gaddafi should leave, that he should spare his people further bloodshed and that in doing so it's clear he has no part in the future of Libya and the National Transitional Council can put forward their proposals which they've thought through very carefully over the last few months to see a new constitutional settlement," he said.
In a statement released by Downing Street on Sunday, the British government called on Libyan leader Muammar Gaddafi to step down without delay.
"It is clear from the scenes we are witnessing in Tripoli that the end is near for Gaddafi. Gaddafi must go now to avoid any further suffering for his own people," it added.
Ed Miliband, Leader of the Opposition Labor Party, said the situation in Libya remained fraught and fragile but "what is clear is that the regime of Colonel Gaddafi is crumbling."
He said anybody looking at the scenes from Tripoli will see a people who want to be freed from the repression which has marked Colonel Gaddafi's rule.
"As we see events unfold in Libya, we should take pride in the role of brave British servicemen and women and the way Britain is working with other countries to enforce the will of the United Nations. The international community has come together on Libya to show it can unite and stop the brutal murder of his own people that Colonel Gaddafi threatened," He added.
Miliband said the challenge now was to ensure that a transition takes place from popular revolt against Colonel Gaddafi to stable government without him.
Libya's charge d'affaires Mahmud Nacua claimed in London that rebel forces were in control of 95 percent of the capital, and the rebel-led National Transitional Council would move its base from the east to Tripoli.
"There will be no vacuum. The NTC will move soon from Benghazi to Tripoli and they will appoint a transitional government which will rule the country," Nacua said.
But Libyan Information Minister Moussa Ibrahim told CNN that the government still had 65,000 loyal soldiers fighting under the Gaddafi's government while a rebel spokesman said those forces still control up to 20 percent of Tripoli.