Islamabad, Jun 7 (IANS): Pakistans polio eradication campaign is in disarray after an alarming jump in cases last week.

Eight polio cases have now been reported in children over the past month in North Waziristan district, bordering Afghanistan, the Guardian reported.

They are the first cases in more than a year.

This new outbreak, officials believe, is due to parents falsely marking themselves and their children as vaccinated, and the government has launched an investigation into the outbreak.

North Waziristan is a former Taliban stronghold in northwest Pakistan, where high vaccine refusal rates are thought to be behind the new cases.

"Fake markings and refusals are two key reasons in the recent outbreak, with polio staff conspiring with parents to miss the vaccination," said an official at Pakistan's polio eradication programme, referring to how parents suspicious of immunisation have got hold of special pens used by health workers to mark vaccinated children's fingers.

Shahzad Baig, national programme coordinator, said: "The cases are highlighting exactly where the challenges lie, and we are doing our utmost to ensure that the virus remains contained and we fight it till the end."

Before this surge, the last case of child paralysis as a result of polio was reported in January last year, the Guardian reported.

Federal Health Minister, Abdul Qadir Patel said: "Following the first two cases in April, the polio programme took immediate steps to ringfence this area and prevent the virus from spreading further, particularly in the historic reservoirs (of infection) of Karachi, Peshawar and Quetta.

Militant groups in Pakistan have killed more than 100 health workers and their security guards since 2012.

According to the World Health Organization, Pakistan is one of only two countries, with Afghanistan, where the wild polio virus is still endemic.