Britain said late on Sunday that the end was near for Libyan leader Muammar Gaddafi, urging him to "go now" to avoid further violence, Xinhua reported.
"It is clear from the scenes we are witnessing in Tripoli that the end is near for Gaddafi," British prime minister's office said in a statement, shortly after reports said that Libyan rebels have launched attacks on the capital Tripoli.
Gaddafi "must go now to avoid any further suffering for his own people," it added.
According to earlier reports by Al-Jazeera TV channel, opposition convoy entered the western district of Tripoli on Sunday with almost no sign of resistance.
Residents of the city began to stream into streets to welcome the opposition troops, despite Gaddafi's call to urge people to take up arms to guard his rule.
The opposition troops were only about 8 km west to the city center, Al-Jazeera reported.