Iran has passed a law requiring immigration officials to fingerprint US passport holders despite President Mahmoud Ahmadinejad's opposition to the measure. A spokesman for the Guardian Council, a constitutional watchdog that must examine all bills before they become law, announced the approval of the legislation Saturday, the official Iranian News Agency reported. "The Guardian Council approved the bill requiring inspecting and fingerprinting American nationals upon arrival in Iran," council spokesman Abbas Ali Kadkhodaei said Saturday, IRNA reported. Kadkhodaei said the government "is required to inspect and fingerprint all American nationals at entry ports and visa issuance centers in consistency with the US behavior." The council approved the law earlier this week, he said. Iran's parliament passed the bill on Nov. 19th. Ahmadinejad last month said he was against the bill because has no quarrel with ordinary Americans. The power to cancel the law lies with parliament and the Guardian Council, which must pass a new legislation that annuls the measure. Conservatives drafted the law in retaliation for the US requirement that Iranian visitors be fingerprinted. The US measure, which also applies to nationals of some other countries, was implemented after the Sept. 11, 2001 terrorist attacks on New York and Washington. Foreign Minister Manouchehr Mottaki last month announced his opposition to the parliamentary bill. Small numbers of American passport holders visit Iran, mostly academics interested in Iran's history and culture.