TRIPOLI (Reuters) - A car bomb exploded near the offices of the military police in Tripoli early on Saturday, a senior security source said, the first such attack in the Libyan capital since the start of a revolt that toppled the regime of Muammar Gaddafi last year.

The source said the blast slightly wounded a Tunisian national, but it could not say who might have been behind it.

A Reuters witness said police had cordoned off the area around the blast's location.

Several violent incidents have rocked Libya in recent days but these have been mostly confined to the eastern city of Benghazi.

Also in Benghazi, seven Iranian relief workers were abducted on Tuesday by an armed group just as they started an official mission as guests of the Libyan Red Crescent Association, which is still seeking to get them released.

(Reporting By Ali Shuaib; Writing by Souhail Karam; Editing by Jon Hemming)