Twenty people were killed in a suicide bombing in a Pakistani market close to the Afghan border.

The attack came a day after the US released letters seized from Osama bin Laden's compound which criticised Pakistani militants for killing too many civilians.

Five of the dead in the blast in the Bajur tribal area were local members of the security forces, including one who had received an award for bravery in fighting Islamist militants, government administrator Abdul Haseeb said.

The others were passers-by.

At least 40 other people were injured.