An explosion at a busy vegetable market in northwestern Pakistan has killed at least 21 people, according to officials.

Around 40 others have been injured in the blast in the Kurram region near the Afghan border.

Sajid Hussain Turi, member of the National Assembly from the region told Reuters there would be a mass funeral followed by a demonstration over the attack.

The Pakistani Taliban and a branch of a sectarian militant group have claimed responsibility for the attack.

Taliban militants have been active around the region in the past, and the town has also suffered sectarian tension between Sunni and Shi'ite Muslims.

Reports differ on the cause of the explosion - however Mr Turi said a homemade bomb had been planted in a pile of tomatoes and exploded as people gathered in the market.