A powerful bomb blast ripped through a busy market outside a religious seminary in Pakistan's restive Khyber Pakhtunkhwa province on Friday, killing at least 30 people and injuring over 40 others, officials said.

The explosive material was planted in the Friday Market (Juma Bazar) in Aurakzai tribal district's Kalaya area. At least 17 people were killed while more than 30 others injured, Geo news quoted district administration officials as saying. The blast occurred outside the door of a religious seminary, it added.

People were buying warm clothes when the bomb went off, officials said.

Officials said most of the victims were minority Shia Muslims, who had been targeted in the area in the past as well.

'Three children were among those killed. The remote-controlled bomb was attached to a motorcycle,' officials said.

The area has been cordoned off and an investigation is under way. An emergency has been declared in the region's hospital.

Human rights minister Shireen Mazari blamed the US failure in Afghanistan for the attack and warned Pakistan to be prepared for more such incidents.

'As the US fails in Afghanistan, Pakistan should be prepared for fallout and we must ensure greater security for our tribal areas especially protection of our people,' she tweeted.

No group claimed responsibility of the attack but the Taliban militants often carry out such attacks.

Khyber Pakhtunkhwa police are on high alert following the Orakzai blast and a separate attack on the Chinese consulate in Karachi on Friday morning.

'Our enemies are not happy with peace in the province,' provincial chief minister Mehmood Khan said after the attack.

In 2011, 30 people including 10 cops, were killed and over 50 injured when a suicide bomber rammed his explosive-laden van into the building of the Communication and Works Department.