A suicide bomber attacked a gathering of displaced people waiting to get aid in northwestern Pakistan on Saturday, killing at least 40 of  them, a hospital official said.

The attack in the Bajaur region on the Afghan border came a day after a big clash between Pakistani Taliban insurgents  and security forces in the neighbouring Mohmand region that  left 11 soldiers and 24 militants dead.

'I myself have counted 40 bodies but the death toll could  rise as several wounded people are in critical condition,'  Dosti Rehman, an official at the main government hospital in  Bajaur, told Reuters.

A government official in Bajaur, Wisal Ahmed, said the  people gathering to get food rations had been forced from  their homes by earlier fighting between the security forces  and the al Qaeda-linked militants.

Pakistan's volatile ethnic Pashtun tribal lands on the  Afghan border have been infested with militants and the army  has mounted a series of operations to dislodge them.

Hundreds of militants have been killed and many of their  strongholds have been captured but the insurgents have shown  the ability to strike back and have killed hundreds of people  in a campaign of bomb attacks across the country.

A senior military official in October said it would take  at least six months to clear militants from Bajaur and Mohmand. – Reuters