PESHAWAR, July 2 (AP): A roadside bomb exploded in Pakistan's northwest Thursday, killing two police officers in the latest attack on the country's security forces as they try to eliminate Taliban insurgents nesting near the border with Afghanistan.

The blast came as the Pakistani military wages a major offensive in the nearby Swat Valley, readies another in the South Waziristan tribal region, and engages Taliban fighters in other spots of the troubled region.

Security forces killed 28 militants late Wednesday in Khyber tribal region, according a statement from the paramilitary Frontier Corps. Some local tribes also have launched militias to take on the insurgents - fighting that has left dozens dead in recent days.