At least five people have been killed and at least 10 wounded after a bomb attached to a bicycle exploded in northwest Pakistan.

No one has claimed responsibility for the blast on Monday near a women's hostel on a busy road in the city of Dera Ismail Khan.

The bomb went off minutes after a provincial politician, Khalifa Abdul Qayyum, had passed by the area on the border with Afghanistan.

Pieces of human flesh littered the ground next to a severely damaged rickshaw and private vehicle, witnesses said.

No one has claimed responsibility for the attack but tribal fighters continue to fight government troops in the volatile region.

Dera Ismail Khan, 270km southwest of the capital, Islamabad, is near the border with the South Waziristan ethnic Pashtun tribal region, a sanctuary for al Qaeda and Taliban militants on the Afghan border.

Fighters have launched a wave of suicide and bomb attacks and assassinations following military operations against them in the northwest, including the Swat valley.