ISLAMABAD, April 13 (Xinhua) -- Unidentified men abducted eight members of a polio vaccination team in northwestern Pakistan on Monday, leaving the medical drive to a halt in the insurgency-hit region.

    The team was busy in vaccination of 6,000 children in Darsmand area of Hangu district, North West Frontier Province (NWFP), near the Afghan border when eight members were kidnapped, a health official told Geo TV channel.

    Pakistan's health ministry has demanded suspension of the polio vaccination drive in Hangu district after the kidnapping.

    There is no clue as to which group carried out the abduction. Police have started search operation for the recovery of abductees.

    There has been increase of polio cases in Pakistan in recent years, most of which is concentrated in the NWFP where some extremists claim that the vaccination could cause infertility and is against Islam.