A strong explosion rocked Yemen's defence ministry complex in the heart of the capital Sanaa on Thursday, an AFP correspondent said.

Plumes of smoke billowed across the complex, situated on the edge of the Baba al-Yaman neighbourhood, and gunfire was heard.

There was no immediate indication of the cause of the blast and it was unclear if there were any casualties.

The incident comes at a time when Yemen is experiencing a surge of violence, and follows a spate of hit-and-run attacks on military and other officials in Sanaa by militants on motorbikes.

The attacks in the capital and in the country's south have been blamed on Al-Qaeda in the Arabian Peninsula (AQAP), which Washington regards as the jihadist network's most dangerous branch.

Yemen has been going through a difficult political transition since veteran president Ali Abdullah Saleh was ousted in February 2012 after a year of deadly protests against his 33-year rule.