Islamabad, Dec 28 (IANS): A polio eradication campaigner was killed when unidentified gunmen sprayed bullets at a hospital in Pakistan's northwest Peshawar city Saturday morning, local media reported.

Two motorcycle riding assailants opened fire at the head of a local polio eradication team at a hospital located in Matani area of Peshawar, the capital city of Pakistan's northwest Khyber Pakhtoonkhwa province.

The campaigner was killed at the spot, and two others, including a woman and a policeman, were injured. They were rushed to Matani hospital for treatment.

No group has claimed responsibility for the attack yet.

Polio teams were being attacked frequently by Taliban militants as they believe that the US is spying on them through the campaigners.

Facing security threats, health workers and polio vaccinators have refused 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 speeded up the eradication campaign.

According to a report released by World Health Organisation (WHO) on Dec 4, 72 cases of polio were found in the country in 2013. In 2012, there were 58 cases.

"Pakistan has reported 72 polio cases which is the highest in comparison to two other countries with the disease, as Nigeria has 50 cases and Afghanistan reported only nine during 2013," Elias Durry, emergency coordinator for the WHO's Polio Eradication Pakistan Program, said.

He said in most cases children were missed in the areas where the law and order situation was not favourable, and where vaccination teams faced security threats.

The WHO warned of the danger of a serious polio outbreak in Pakistan's northwest, saying more than 240,000 children had missed vaccination because of the Taliban ban and threats.