Iran’s reformist opposition on Wednesday delivered a co-ordinated message to Iranians, declaring the government of Mahmoud Ahmadi-Nejad illegitimate and encouraging supporters to challenge it. A statement by Mir Hossein Moussavi, the opposition leader who says the June 12 election was rigged in favour of the hardline Mr Ahmadi-Nejad, followed similarly defiant calls by Mosharekat, Iran’s largest reformist party, and Mehdi Karroubi, the second reformist candidate.Mohammad Khatami, the former reformist president and a strong supporter of Mr Moussavi, also joined the chorus warning that the regime, with its “poisonous propaganda” against protesters and its security crackdown, was waging a “velvet revolution” against the “people and the system’s republicanism”. The concerted effort came two days after the Guardian Council, the constitutional watchdog dominated by hardliners, confirmed the election result. It underlines the determination of the opposition to undermine Mr Ahmadi-Nejad’s presidency.A huge security crackdown has restricted the opposition’s ability to organise protests, but the refusal of reformist leaders to accept the election result could discourage western governments from dealing with Mr Ahmadi-Nejad.