Sustained automatic gunfire and a series of explosions have rung out in Tripoli, according to reports from the Libyan capital.
Blasts and gunfire rocked the city after sunset on Saturday, and witnesses reported fighting in the eastern neighbourhoods of Souq al-Jomaa, Arada and Tajoura.
A government spokesman had earlier said an attack on Tripoli by rebels seeking to depose Muammar Gaddafi had been "dealt with".
"Sure, there were some armed militants who escaped into some neighbourhoods and there were some scuffles, but we dealt with it within a half hour and it is now calm," Moussa Ibrahim said.
"The situation is under control," Ibrahim said on television, adding that pro-regime volunteers had repelled insurgents’ attacks in several neighbourhoods.
Ibrahim dismissed mounting speculation that the regime was on the brink as a "media attack," but more gunfire was heard after he spoke on television.
In a live audio broadcast aired on state television early on Sunday morning, Gaddafi congratulated his supporters for repelling an attack by rebel "rats".
Gaddafi accused French President Nicolas Sarkozy of trying to steal the country's oil and said that the rebels were "bent on the destruction of the Libyan people".
Gun battles and the explosion of apparent mortar rounds could be heard clearly at the hotel where foreign correspondents stay in the capital. Their movements are tightly restricted by the regime.