Riaz Khan Mehsud, deputy commissioner of Peshawar told AFP that 471 parents were detained and sent to jail for refusing the vaccine.Pakistan is one of only three countries in the world where polio remains endemic but years of efforts to stamp it out have been badly hit by reluctance from parents, opposition from militants and attacks on immunisation teams.The virus is most prevalent in Khyber-Pakhtunkhwa and a fresh immunisation drive began on Monday aimed at vaccinating more than 2.7 million children in the province.The government declared "war" on polio last year and Mehsud said officials would brook no refusal from parents."There is no mercy, we have decided to deal with the refusal cases with iron hands. Anyone who refuses (the vaccine) will be sent to jail," Mehsud said.Those arrested on Monday were from suburban areas of Peshawar where militant groups regularly attack police and polio workers and where opposition to vaccination is relatively strong.Mehsud said authorities have issued 1,000 blank arrest warrants so refuseniks could be dealt with swiftly.Muhammad Mumtaz, another senior official, confirmed the arrests and told AFP that the detainees would "be freed only after a written assurance and providing two guarantors" to ensure their children get the drops.Taliban militants claim that the polio vaccination drive is a front for espionage or a conspiracy to sterilise Muslims. They stepped up their attacks after a Pakistani doctor was recruited by the CIA to set up a hepatitis immunisation drive as part of efforts to track down Al-Qaeda chief Osama Bin Laden.Last year, the number of polio cases recorded in Pakistan soared to 306, the highest in 14 years.At least nine new cases have so far been detected in 2015.