More than 39 people died in an explosion in Pakistan and dozens more were injured in the north-west Bajaur area, where the Jamiat Ulema-e-Islam-Fazl (JUI-F) was holding a rally.

Authorities have roped off the area and warned that the number of casualties may still increase.

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The rescue mission to aid the injured is still underway, and authorities have not yet determined the cause of the explosion.

Images shown on local television show ambulances transporting injured individuals to hospitals in the Pakistani tribal area of Bajaur, in Khyber Pakhtunkhwa province near the Afghan border.

Some seriously injured persons have been waiting in the halls of health centers that have been overwhelmed by the large number of victims.

The district hospital has been designated a health emergency by the authorities.

According to local officials, the bomb killed Maulana Ziaullah, a regional head of the JUI-F.

Riaz Anwar, the health minister for Khyber Pakhtunkhwa province, told AFP, "I can confirm that in the hospital we have 39 dead bodies, with 123 wounded that includes 17 patients in a serious condition."

The provincial governor Haji Ghulam Ali also confirmed the death toll to AFP.