Iranian President Mahmoud Ahmadinejad defended his re-election at a mass victory rally on Sunday but his defeated rival demanded the result be scrapped, setting the stage for further confrontations after a crackdown on opposition protests. Violence erupted for the second day in Tehran as supporters of Amadinejad's closest challenger Mir Hossein Mousavi clashed with riot police after an election that has set off deep divisions in the oil-rich republic. Addressing a sea of thousands of flag-waving supporters packed into central Tehran, the hardline Ahmadinejad denied the result of Friday's vote that have given him another four years in power was 'distorted.' 'Elections in Iran are the cleanest,' he said. 'Today, we should appreciate the great triumph of the people of Iran against the unified front of all the world arrogance (the West) and the psychological war launched by the enemy.' But after a massive opposition backlash, Western nations have raised concerns about the legitimacy of the vote and the subsequent crackdown on dissidents and protesters. The moderate Mousavi said he has lodged an appeal with the powerful Guardians Council to cancel the results of the election, which he has charged was a 'charade' and marred by blatant fraud. Another defeated candidate, Mohsen Rezai, also complained to the Guardians Council, said its spokesman, Abbas Ali Kadkhodai, quoted by ISNA news agency. 'We will announce the result after examination' of the complaints, he said. US Vice President Joe Biden said there was 'an awful lot of doubt' about the vote, while European nations voiced concern at what Germany called 'unacceptable' action by security forces against protesters. Hundreds of flag-waving demonstrators gathered outside Iranian embassies in Europe to denounce Ahmadinejad's re-election, notably in London, Berlin and Brussels. Police said they rounded up 170 people over Saturday's protests in Iran, which triggered violence on a scale not seen since 1999 when student demonstrations led to a week of deadly nationwide unrest. Amnesty International called for the Iranian authorities to immediately investigate the crackdown on demonstrators. 'The shocking scenes of violence meted out by the security forces need to be urgently investigated and those responsible for human rights violations must be brought to justice,' it said. On Sunday, police fired into the air to break up a demonstration, while about 200 Mousavi supporters shouting 'Death to the dictator!' lobbed stones at police who fired back with tear-gas. Among those arrested were reformist leaders including several people who served under reformist former president Mohammad Khatami. Iranian authorities blocked German ARD and ZDF public television journalists from covering the protests, their editors said, and two Dutch journalists were arrested and ordered to leave the country. The BBC said satellites were jammed and that a journalist and a cameraman had been briefly arrested, while Arab news channel Al-Arabiya said its Tehran office had been shut down for a week. The election results dashed Western hopes of change after Ahmadinejad's first term set Iran on a collision course with the international community over its nuclear drive, his anti-Israeli tirades and restrictions on society. Official results gave Ahmadinejad 63 percent of the vote against just 34 percent for Mousavi, despite some expectations he had done enough to fight a second- round runoff. The 52-year-old Ahmadinejad said the election was like a football match and the loser should just 'let it go.' Mousavi said however he had sought permission to hold rallies on Monday, calling on his supporters to turn out in green, his signature colour. Supreme leader Ayatollah Ali Khamenei, who has the final say on all strategic matters including foreign and nuclear policy, has urged the country to unite behind Ahmadinejad. The election campaign, with its mudslinging candidate debates and mass street rallies, appears nevertheless to have galvanised a grass-roots push for change. It highlighted deep divisions in Iran, with massive support for Ahmadinejad in the rural heartland and among the poor, while in the big cities young men and women threw their weight behind Mousavi. US President Barack Obama has called for dialogue after three decades of severed ties. But US analysts warned Ahmadinejad's return would complicate efforts to resolve the standoff over Iran's nuclear drive, which the president said on Sunday was 'history'. In Israel, Prime Minister Benjamin Netanyahu said the 'biggest threat to Israel, the Middle East and the entire world is the crossing of a nuclear weapon with radical Islam.' 'During my next trips, I will work in particular toward an international coalition against the nuclear arming of Iran,' he said. The West fears Iran is seeking atomic weapons, charges denied by Tehran which has defied international demands to halt uranium enrichment despite UN sanctions. Russia, which is helping Iran build its first nuclear powr plant, said Ahmadinejad would meet President Dmitry Medvedev this week to discuss the nuclear issue. 