More than 30 rebels including field commanders were killed Sunday in a huge explosion of a ammunition depot in the country's central province of Homs, activists and local media said.

Homs-based activists said the huge explosion at the Jouret al- Shayah area in the old quarter of Homs was caused by a government troops' Grad missile that slammed into a reserve ammunition depot, which was prepared by the rebels in a bid to unleash an offensive against the government troops to break the year-long siege on rebel-held areas inside the old city of Homs.

Other activists, however, said the blast was caused by a booby- trapped car that tore through the depot.

Meanwhile, the pro-government al-Khabar website said the blast was caused by the government troops' artillery shelling on the ammunition depot, which killed more than 30 rebels, including Abdul-Qader Juma, the head of the military council of the rebels Free Syrian Army and Eyad Zugaib, another field commander.

Further details about the blast are still forthcoming amid the absence of official statements.