Islamabad, Jan 11 (IANS): Around 70 health workers in Pakistan's Khyber Agency area refused to take part in a polio vaccination campaign Saturday citing security concerns, a media report said.

"We feel threatened and everyone is frightened after the killing of our colleagues last month," Dawn newspaper quoted Haji Sadeeq, a spokesman for the workers, as saying.

The workers said it was not possible for them to conduct the door-to-door campaign because of the presence of militants in the area.

The spokesman said the workers were ready to sacrifice their jobs if they were forced to conduct the vaccination.

Polio workers in Pakistan are frequently attacked by Taliban militants.

Facing security threats, health workers and polio vaccinators refuse to go into the country's tribal areas, hampering the government's efforts to root out the disease.

Pakistan is one of the world's three countries along with Afghanistan and Nigeria where polio still exists.

In 2011, an estimated 173 cases of polio were registered in Pakistan, following which the government stepped up the eradication campaign. In 2012, there were 58 cases.

According to a report released by the World Health Organisation (WHO) Dec 4, 2013, around 72 cases of polio were found in the country last year.