TEHRAN (Reuters/AFP) - A provincial official said on Friday those behind a mosque bombing that killed around 20 people in Iran had been hired by the United States, Tehrans arch-foe, a semi-official news agency reported. Jalal Sayyah, at the governors office in Sistan-Baluchestan province, said three people had been arrested in connection with Thursday evenings blast in a crowded mosque in the southeastern city of Zahedan, near Pakistan. The explosion, which some Iranian news agencies say may have been a suicide bombing, took place on a religious holiday two weeks before the June 12 presidential election in the Muslim country dominantly of Shia sect. More than 80 people were wounded. It has been confirmed that those behind the terrorist act in Zahedan were hired by America and the arrogances other hands, Sayyah told Fars News Agency. Iranian leaders, who often accuse the United States and its allies of seeking to destabilise it, refer to Washington as the Great Satan guilty of global arrogance. Iran says a Sunni rebel group, Jundollah (Gods Soldiers), which has been operating in the border region is part of the Sunni Al -Qaeda network and has accused the United States and Britain of backing it. Meanwhile, gunmen attacked President Nejads election campaign centre in the southeastern Iranian city of Zahedan on Friday, wounding three people including a child, the official IRNA news agency said. IRNA said the gunmen, on motorcycles, opened fire at the centre at around 1430 GMT. The attack comes a day after a suicide bomber killed 25 people others in an attack on a Shiite mosque in Zahedan, in Sistan-Baluchestan province bordering Pakistan and Afghanistan. Three knife-wielding people on motorbikes stopped outside the centre on Saadi Street, cursed, made threats and tore up billboards, Mohammad Reza Zahed Sheikhi, who heads Ahmadinejads election office in Zahedan, told IRNA. He said that as the campaign workers went towards them to protest, the attackers pulled out guns and shot at them. He said two campaign workers, Nasser and Khodadad Miri, received arm, stomach and shoulder wounds and were taken to hospital. The child was also shot in the stomach and was undergoing surgery, he told IRNA. The men ran away, but the police chased and arrested them, Sheikhi said.