SWABI: Gunmen attacked two separate polio teams in northwestern Pakistan on Friday, killing one polio worker and two police guards.

The first incident took place in Swabi in northwestern Khyber Pakhtunkhwa province where unknown motorcyclists shot down two policemen on their way to provide security cover to a polio team, local police said.

According to police, the two police officials were on their way to perform security duties when unknown gunmen opened fire on them on Topi Road in Swabi. Subsequently, one police official was killed on the spot while the other, sustaining severe injuries, succumbed to his wounds at the hospital.

Hours later, a gunman killed a polio worker on his way home after vaccinating children in Jamrud district of Khyber tribal region located on the outskirts of Peshawar.

Government administrator Iqbal Khan said the slain worker was targeted for participating in the government-run anti-polio campaign in the tribal area.

Pakistan is one of only three countries in the world where the polio virus is still endemic, but efforts to stamp out the crippling disease have been hit by repeated attacks on health teams.

Officials blame the violence and suspicions about the vaccine for a surge in cases. According to the World Health Organisation, Pakistan recorded 72 cases of polio this year compared to 58 in 2012.

New Delhi on Wednesday announced it would require citizens from Pakistan and other polio-affected nations travelling to India to take a mandatory polio vaccination at least six weeks prior to their departure.