KARACHI: Attackers threw two grenades at the Saudi consulate building in Pakistan's largest city of Karachi on Wednesday, in possible reaction to the US killing of Osama bin Laden, an official said.

There was no damage and no casualties after two men on a motorcycle threw the devices at the heavily fortified building in Clifton, nine days after bin Laden was killed in Pakistan.

“There were no casualties. We are seeing this incident in the present context. It could be a reaction of the Osama incident,” he added.

US Navy SEALs flew into Pakistan, seemingly undetected, to identify and kill the Saudi-born al Qaeda terror mastermind at a suburban compound in Pakistan's city of Abbottabad before dawn on May 2.

An AFP photographer said ambulances, police and paramilitary Rangers swarmed outside the Saudi consulate after the attack, where small shrapnel marks could be seen on the outer wall of the building.

Mohammed Safdar, a police official at the scene, said security guards at the diplomatic mission had opened fire on the attackers but they escaped.

“Two men riding on a motorbike hurled two grenades towards the consulate. The security men at the gate opened fire on them, but they managed to flee,” he told AFP.

“The security guards informed us and we reached the spot immediately. The bomb disposal squad are here. Other police and Rangers have surrounded the area,” he added.

Pakistan is holding in protective custody three of bin Laden's widows, who come from Saudi Arabia and Yemen, and 13 of their children.

The foreign ministry says it has yet to receive a formal request from the United States for access to the relatives or requests from their home countries for their repatriation.