At least 42 people were killed and over 130 injured when a suicide bomber set off explosives at a political rally in Pakistan's northwestern Khyber Pakhtunkhwa province on Sunday, police and rescue officials said.

The blast took place at a gathering of the conservative Jamiat Ulema Islam-Fazl (JUI-F) party, known for its links to hard-line political Islam, in the former tribal area of Bajaur, which borders Afghanistan.

An emergency has been declared in the hospitals of Bajaur and adjoining areas where most of the injured were taken, said district police officer Nazir Khan. The critically injured were transported from Bajaur to hospitals in the provincial capital Peshawar by military helicopters.