At least 40 people were killed and dozens others were wounded in a bomb blast targeting a political rally in the Bajaur district of Pakistan's northwest Khyber Pakhtunkhwa Province on Sunday, according to Geo News.

The blast hit a political workers' convention of the conservative Jamiat Ulema-e-Islam-Fazl party - known for its links to hardline political Islam - near the Shanday Mor area, a spokesperson of the state-run rescue organization Rescue 1122 in Khyber Pakhtunkhwa, said.

Following the blast, police, security forces and rescue teams rushed to the site, and were transferring the dead and injured to nearby hospitals.

According to local media reports, around 500 people were present at the site, and local leaders were delivering speeches when the blast took place.

Police and security forces have cordoned off the area and launched a search operation.

The nature of the explosion is not known yet, nor has any group claimed responsibility.

Pakistan has seen a resurgence of attacks by Islamist militants since last year when a ceasefire between the Tehreek-e-Taliban Pakistan (TTP) and Islamabad broke down.

The TTP pledges allegiance to, but is not directly a part of, Afghanistan's Taliban.

(With input from agencies)