A powerful explosion has occurred outside the front gate of the German embassy in the Afghan capital Kabul, with no immediate reports of injuries.

Afghanistan's interior ministry could not say what had caused the blast, whether it was a suicide attack or a device planted in a vehicle.

The Wazir Akbar Khan district is in a central and sensitive area of Kabul.

Taleban militants have bombed Afghan government and foreign interests in the city in the past.

The embassy caught fire after the explosion which destroyed several vehicles, according to an Associated Press reporter at the scene.

Emergency vehicles are at the scene and fire-fighters are attempting to extinguish the flames, the reporter says.

Philipp Wendel, press officer for the German embassy, said he could not give any details.

AP notes that the embassy stands opposite a US base.