Officials say a roadside bomb has killed at least eight Pakistani soldiers in the country's northwest.

The bomb exploded as a paramilitary convoy was passing through the town of Bara in the Khyber tribal agency early Thursday.

No one claimed responsibility for the blast, but Pakistan's military has been battling Taliban and al-Qaida-linked militants in the country's northwestern tribal region.

The attack comes a day after the Pakistani Taliban released a video showing the heads of 17 Pakistani soldiers captured during a cross-border attack in the Upper Dir tribal agency.

Elsewhere in Pakistan on Thursday, authorities say a bus carrying Shi'ite pilgrims was attacked in the southwestern province of Baluchistan. At least eight people were killed in the blast.

The bus was traveling from Iran to Quetta, the capital of Baluchistan. The province has seen sectarian violence between majority-Sunni Muslims and minority Shi'ites.

A day earlier, a bomb has exploded at a railway station in the Baluchistan, killing at least five people and wounding more than 20 others in Sibi city.

There were no immediate claims of responsibility.