PESHAWAR, Pakistan - Gunmen attacked a polio vaccination team in northwest Pakistan on Tuesday killing a health worker and two policemen -- the latest deaths in a dangerous campaign to eradicate the disease.

Pakistan is one of two countries, alongside neighbouring Afghanistan, where polio remains endemic, but where vaccination teams have been targeted by militants.

"Gunmen came on a motorcycle and opened fire on the vaccination team," senior police offer Ashfaq Anwar told AFP, adding that a child was also wounded by stray bullets.

"The victims died at the scene and the gunmen escaped."

The attack happened in North Waziristan, a region that borders Afghanistan and which was once a significant refuge for Afghan and Pakistan Taliban militants.

Shahid Ali Khan, a senior government official in the district, confirmed the incident.

Scores of polio workers and security officials guarding them have been killed in militant attacks since 2012.

Militancy in the border regions of Pakistan has been on the rise since the Afghan Taliban took back power last year in Afghanistan, with security officials often the target.

Efforts to eradicate polio have been hampered by conspiracy theories spread by the radical religious right, which claim vaccination programmes are part of a Western plot to sterilise Muslims or that vaccines contain pig fat and are therefore banned by Muslims.

Islamist opposition to all forms of inoculation grew after the CIA organised a fake vaccination drive to help track down Al Qaeda's former leader Osama Bin Laden in the Pakistani city of Abbottabad.

Pakistan launched its latest vaccination drive on Monday, aiming to inoculate more than 12.6 million children.

In April, Pakistan reported the first case of the debilitating neurodegenerative disease in 15 months.

Since then, 11 polio cases have been reported -- all from the same ultra-conservative district where many villagers are against the vaccines.