TRIPOLI - A heavy explosion rocked east the Libyan capital of Tripoli late Tuesday evening, causing a big fire, with helicopters of the NATO forces hovering over the area, a Xinhua correspondent said.

Huge columns of smoke can be seen arising from the district of Fernaj, in east Tripoli, according to the Xinhua correspondent.

Libyan state TV later confirmed the blast, without indicating the casualties from the incident.

During the past several weeks, NATO forces have intensified strikes against Tripoli and the neighboring areas. Libyan authorities have continually accused NATO of killing hundreds of civilians and destroying civil facilities and infrastructures.

The world's major powers, the UK, the US and France, started on March 19 to launch strikes from the air and sea against Gaddafi 's forces after the UN Security Council passed a resolution to impose a no-fly zone over Libya and authorize "all necessary measures" to protect civilians in Libya.

NATO has formally taken over full command and control of military operations against Libya from the US on March 31.