Police say one man is in custody for the attack, which occurred some 30km north-west of Islamabad.

The first blast took place outside the gate of the factory as workers were leaving work during a shift change. Minutes later, another blast took place at a market near another gate of the same factory.

A spokesman for the Pakistani Taleban said they had carried out the attacks, which he said were a response to army violence in the country's north-west. He said more attacks would take place in Pakistan's major urban areas unless the army withdrew from tribal areas.

Pakistani Prime Minister Prime Minister Yousef Raza Gilani promised to punish the perpetrators.

US President Bush later telephoned Mr Gilani to pledge his support in tackling what he called terrorist attacks.

Earlier on August 19, 32 people were killed in a suicide attack on a hospital in the northern town of Dera Ismail Khan.