An explosion damaged a Libyan foreign ministry building in Benghazi, local officials said today, the first anniversary of the attack on the US consulate in the country's second largest city.

Officials said the car bomb exploded at dawn, badly damaging the ministry office and several other buildings in the centre of Benghazi, but there were no immediate reports of casualties.

"The car had a large amount of explosives and was placed just next to the building," said Abdullah Zaidi, a local security official told Reuters.

Two years after the revolt that toppled Muammar Gaddafi, Libya is deeply split along regional and tribal lines, leaving the central government in Tripoli struggling to control the influence of rival militias and radical Islamists.

The central government is also trying to end strikes by oil workers and armed guards at oil installations that have paralyzed the North African state's crude production.

Four Americans including the US envoy to Libya were killed in an attack on the consulate in Benghazi a year ago. Washington initially said the assault had grown out of anti-Western protests. But it later turned out that Islamist militants were the perpetrators, marking the 11th anniversary of al Qaeda's September 11 attacks on the United States.