A shell fired near a Yemeni general's military headquarters in the capital Sanaa hit a weapons depot on Thursday, setting off a series of explosions.

A Reuters witness said he heard two blasts and saw a large cloud of dust above the camp where General Ali Mohsen Al-Ahmar is based.

Ahmar defected during last year's uprising, and now leads part of the army under President Abd-Rabbu Mansour Hadi.

A source in Ahmar's force, known as the First Division, said a shell fired from outside the headquarters had landed on an ammunition cache, setting off the explosions.

He added that there were no casualties and an investigation was underway to determine who had fired the shell.

The Yemeni Defence Ministry said the blasts were caused by an accident in an ammunition depot.