EDIT CONTAINS 4:3 MATERIAL
A suicide bomber killed at least 15 people and wounded 40 on Friday (May 4) in an attack on a police checkpoint in northwest Pakistan, casting doubt on official assertions that security offensives have weakened militants.
The bomber struck near a crowded market in Bajaur, one of the unruly Pashtun tribal regions near the Afghan border where the military has mounted offensives in recent years against the al Qaeda-linked Pakistani Taliban, the biggest security threat to the country.
Officials say at least three of the dead were policemen, including a senior officer.
Police and security forces sealed off the site of the attack.
Pakistan, a strategic U.S. ally, has failed to break the back of the Taliban despite numerous crackdowns. The Taliban have mounted suicide bombings, which have often killed civilians, and shooting attacks on security forces in their bid to topple the government.