A blast rocked the central Damascus district of Marjeh on Tuesday causing casualties, Syrian state television said, with an AFP correspondent reporting automatic arms fire after the explosion.

"Terrorist explosion in Marjeh district of Damascus and preliminary information on casualties," state television reported.

The explosion, which state media said also caused damage at the scene, came near an interior ministry building.

The Syrian Observatory for Human Rights watchdog said the blast was caused by a car bomb that detonated by the building's back door, adding that there were dead and wounded after the explosion.

It came a day after the blast in the Mazzeh neighbourhood of the capital targeting Prime Minister Wael al-Halqi.

The car bomb, which exploded as his convoy passed through the upscale neighbourhood, killed one of his bodyguards and five other people, according to the Observatory.

Damascus has seen a wave of major bombings in recent weeks, including on April 9, when a massive blast in the centre of the city killed at least 15 people.