Six police officers have died and 10 other people were hurt after a roadside bomb exploded near a van carrying police assigned to protect workers in a polio immunisation campaign in north-western Pakistan.

The Pakistani Taliban claimed responsibility for the attack.

The bombing happened in the former Pakistani Taliban stronghold of Mamund in Khyber Pakhtunkhwa province bordering Afghanistan, police official Kashif Zulfiquar said.

He said some of the wounded officers were in a critical condition in hospital.

Anti-polio campaigns in Pakistan are regularly marred by violence.

Islamic militants often target polio teams and police assigned to protect them, claiming falsely that the vaccination campaigns are a Western conspiracy to sterilise children.

In a statement, the Pakistani Taliban claimed responsibility for Monday’s attack, which came hours after authorities launched the first anti-polio campaign of the new year.

The Pakistani Taliban, also known as Tehreek-e-Taliban Pakistan (TTP), is a separate group but a close ally of the Afghan Taliban, who seized power in Afghanistan in August 2021 as US and Nato troops were in the final stages of their pullout from the country after 20 years of war.

Many TTP leaders and fighters have found sanctuaries in Afghanistan since the Taliban takeover, which also emboldened the TTP to carry out more attacks on security forces.

It has strained Pakistan’s ties with the Taliban government, which insists it does not allow TTP to use its soil to launch attacks in Pakistan.

Mr Zulfiquar said the campaign has been halted in the area where the attack occurred and all the polio workers are safe. Authorities said it will continue in other parts of the country.

Pakistan and Afghanistan are the only countries in the world where polio remains endemic. Last year, at least six new polio cases were detected in Pakistan, almost all in the north-west where parents often refuse to inoculate children.

The outbreak has been a blow to the nation’s efforts to eradicate the disease, which can cause severe paralysis in children.

In 2021, Pakistan reported only one case, raising hopes it was close to eradicating polio. Other cases then began being detected despite anti-polio efforts.