A burqa-clad suicide bomber, believed to be an Afghan national, blew herself up at an army check post near a convent school in north-western Pakistan, in the country's first known case of a suicide attack by a woman bomber.

The woman bomber, who was wearing a blue burqa, was killed but there were no other casualties in the attack, which took place on the outskirts of Peshawar, the capital of North West Frontier Province. No group has claimed responsibility for the incident -- which was the first known case of a woman carrying out a suicide attack in Pakistan.

The bomber, who was in her 30s, was trying to reach an unmanned check post outside an intelligence agency office in the area and detonated the explosives when some security personnel spotted her, police officer Tanveer-ul-Hasan Sepra said. The explosion occurred near St Mary's Convent, one of the best schools in Peshawar.

It also took place in the highly sensitive cantonment area of the NWFP capital, where several offices of the army and intelligence agencies are located. The police said that the woman could be an Afghan national as she was wearing Afghan clothes.