A suicide bomber reportedly detonated his explosives at the southern gate of Bagram Airbase in Parwan province on Wednesday evening.

Interior Ministry spokesman Najib Danish says the explosion was carried out by a suicide bomber riding a motorbike.

He said three civilians were wounded in the blast and that two of them are in a critical condition.

Bagram district governor however says four people were wounded in the bombing.

This comes just hours after a senior US commander in Afghanistan apologized on Wednesday for a highly offensive propaganda leaflet that had been distributed by US forces in Parwan, just north of Kabul, on Tuesday.

The offensive leaflet contained a passage from the Quran used in the Taliban militants� banner superimposed on to the image of a dog.

The dog is considered unclean in Islam and associating an image of the animal with one of the religion�s most sacred texts prompted indignation.

The image showed a white dog with a section of the Taliban�s banner superimposed on its side fleeing from the lion. The banner contains a passage from the Quran in Arabic.

The design of the leaflets mistakenly contained an image highly offensive to both Muslims and the religion of Islam, Major General James Linder said in a statement.

I sincerely apologize. We have the deepest respect for Islam and our Muslim partners worldwide, he said, adding that an investigation would be held to determine the cause of this incident and to hold the responsible party accountable.