Iran claims it has detained alleged US-based opposition leader Jamshid Sharmahd over a bomb attack which killed 14 people. Iranian intelligence services said on Saturday it had detained a leader of a pro-monarchist group whom it accused of being behind a deadly 2008 bombing and of plotting other attacks. An intelligence ministry statement cited by state television did not say how, where or when the detention took place. “Jamshid Sharmahd, the ringleader of the terrorist Tondar (Thunder) group, who directed armed and terrorist acts in Iran from America, was arrested following a complicated operation, and is now in (our agents') powerful hands,” it said. Its state television showed a video of a man identifying himself as Mr Sharmahd and giving his date of birth. The man was later shown with a blindfold, saying: "They needed explosives and we provided it." Hamid Baeidinejad, Iran's ambassador to Britain, said on Twitter that Mr Sharmahd "is in custody in Iran". Tondar did not confirm the detention. The US State Department did not immediately respond to a request for comment. Based in Los Angeles, the Kingdom Assembly of Iran, also known as Tondar, says it seeks to restore the Iranian monarchy that was overthrown by the 1979 Islamic revolution. It runs pro-Iranian opposition radio and television stations abroad. According to the group’s website, Mr Sharmahd is an electronics engineer who was born in 1955. The website said he is Iranian-German and lived in Germany before moving to Los Angeles in 2003. No comment was immediately available from the German foreign ministry. The Iranian ministry statement said Mr Sharmahd had planned and directed an explosion at a religious center in the southern city of Shiraz in 2008 that killed 14 people and wounded 215. It said Iranian intelligence aborted several other plots in more recent years, including blowing up the shrine of Ayatollah Ruhollah Khomeini. It did not say when the alleged plot was aborted. It said further details of Mr Sharmahd's detention would be announced later. The Iranian foreign ministry said in a statement the United States "must be held accountable for backing this terrorist group and other groups and criminals responsible for sabotage, armed and terrorist operations ...from within the United States and shedding the blood of Iranian citizens."