At least three policemen and two security guards of a foreign-funded tourist centre were injured in a bomb attack in northwest Pakistan on Thursday.

The blast was carried out through remote control near a police check-post and the Austrian-funded Pethem Tourism Centre at Mingora in Swat valley of North West Frontier Province, police said.

No group claimed responsibility for the attack, but the authorities blamed the attack on militants opposing the government crackdown on Islamic extremists.

The injured were taken to a local hospital. Doctors said that two injured policemen are in a critical condition.

Bomb blasts and suicide attacks against security forces have increased after the army stormed the Taliban-linked Red Mosque in Islamabad and the Pakistani Taliban scrapped a peace deal with the government in the troubled tribal region in July.