KUNDUZ, (Afghanistan): A suicide bomb attack on worshippers at a Shia mosque in the Afghan city of Kunduz killed at least 55 people Friday, in the bloodiest assault since US forces left the country.

Scores more victims from the minority community were wounded in the blast, which has not been claimed but appears designed to further destabilise Afghanistan in the wake of the Taliban takeover.

The extremist Islamic State group, bitter rivals of the Taliban, has repeatedly targeted Shias in a bid to stir up sectarian violence in Sunni-majority Afghanistan.

Matiullah Rohani, director of culture and information in Kunduz for Afghanistan's new Taliban government, confirmed to AFP that the deadly incident was a suicide attack.

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A medical source at the Kunduz Provincial Hospital said that 35 dead and more than 50 wounded had been taken there, while a worker at a Doctors Without Borders (MSF) hospital reported 15 dead and scores more wounded.

Taliban spokesman Zabihullah Mujahid had earlier said an unknown number of people had been killed and injured when "an explosion took place in a mosque of our Shia compatriots" in Kunduz.

Residents of Kunduz, the capital of a province of the same name, told AFP the blast hit a mosque during Friday prayers, the most important of the week for Muslims. Zalmai Alokzai, a local businessman who rushed to Kunduz Provincial Hospital to check whether doctors needed blood donations, described horrific scenes.

"Ambulances were going back to the incident scene to carry the dead," he said.

An international aid worker at the MSF hospital in the city told AFP there were fears the death toll could rise even further.