The blast underscores the threat posed by Islamist militants blamed for near-daily attacks in Pakistan. It was the first bombing in the capital Islamabad since last September, when more than 50 people were killed in a suicide truck bomb attack on the Marriott Hotel.

Interior Ministry secretary Kamal Shah says a man detonated explosives at the gate of a police station close to a market in the center of the capital. He said an officer who was apparently challenging the attacker died in the blast. There were no immediate reports of any other casualties.

Pakistan is under intense Western pressure to crack down on the militants, many of which are believed linked to al Qaeda. They are also blamed for attacks on U.S. troops in neighboring Pakistan. The terrorists are believed to have established havens in tribal regions close to the Afghan border.