At least 44 people were killed and dozens more wounded Sunday by a suicide bombing at a political gathering of a leading Islamic party in northwest Pakistan.

The blast targeted the Jamiat Ulema-e-Islam-F (JUI-F) party, as hundreds of supporters congregated under a canopy in the town of Khar, near the Afghan border.

Sabeeh Ullah, a 24-year-old party supporter who had his arm fractured by the blast,  told reporters that the scale of injuries was horrifying.

Images from the blast site circulating on social media showed bodies strewn around the scene, and volunteers helping blood-soaked victims to ambulances.

Access24 reports that Pakistan's national assembly is due to dissolve in the next few weeks ahead of elections expected in October or November, and political parties are already preparing to campaign.

The blast coincides with a visit to the country by a senior delegation of Chinese officials, including Vice Premier He Lifeng, who arrived in the capital Sunday evening.