New York's main contract, light sweet crude for September delivery, was upward 82 cents to $83. 08 a barrel from Friday's close in Ny and Brent North Sea crude for October delivery dropped $1. 59 in order to $107. 03.
"This is really the main news event, " Victor Shum, a good analyst with energy consultancy Purvin and Gertz in Singapore, said of the problem unravelling in Libya.
"Rebels have entered Tripoli... There have also been reports Gaddafi will get free from the country, " Shum told AFP.
Libyan rebels surged into Tripoli yesterday inside a final drive to oust Gaddafi as they seized swathes of the funds including symbolic Green Square and arresting the strongman's son, Seif al-Islam.
Nevertheless, senior rebel figure Mahmud Jibril said there were still pockets of resistance around Tripoli and warned his forces to be cautious.
"The fight is not really over yet, " he said on rebel television Al-Ahrar. "God willing, in few hours our victory is going to be complete. ".