Gunmen on motorbikes opened fire on health workers and police carrying out a door-to-door polio vaccination drive in Pakistan, killing one officer, officials said on Tuesday.

The latest attack targeting the campaign occurred in the town of Naushki in the restive south-western province of Balochistan during a third nationwide vaccination drive this year, police official Mohamed Hussain said.

The health workers escaped unharmed as attackers fled the scene after the shooting, Hussain said.

No group has claimed responsibility so far, but both the Pakistani Taliban and Islamic State militias are active in the region and have been targeting polio vaccination campaigns.

At least two officers were killed in Balochistan last month while escorting the UN-funded drive that is carried out periodically across Pakistan.

Pakistan and neighbouring Afghanistan are among the last countries still struggling with the crippling disease despite eradication from all other parts of the world.

Islamist militants who target the polio health workers and security forces accompanying them consider the vaccination drive a conspiracy by the West to sterilise Muslims.

About 200 polio workers and officers have been killed since 2012 when the first attacks were launched.

(dpa/NAN)