The blast took place in the Scheme Chowk neighbourhood of Peshawar.

"A nine-year old boy was killed and three others, two children and a man, were wounded in the bomb blast," senior police official Tahir Ayub told AFP.

It was a remote-controlled device, bomb disposal squad chief Hukam Khan said.

Nobody claimed the responsibility for the blast but Islamist militants have carried out several attacks in the area.