TEHRAN (Reuters/AFP) - Iran detained more than 100 reformers including the brother of a former president, a leading reformer said on Sunday, after violent street protests in Tehran against the re-election of President Mahmoud Ahmadinejad. The President defended his re-election at a mass victory rally but his defeated rival demanded the result be scrapped, setting the stage for further tense confrontations after the authorities cracked down on Opposition protests. Violence continued for the second day in Tehran as supporters of former reformist president Mir Hossein Mousavi clashed with riot police after the election that has set off deep divisions in the oil-rich republic. Supporters of defeated moderate candidate Mirhossein Mousavi, who has dismissed Ahmadinejads election victory to a second term as a 'dangerous charade, gathered in the centre of the capital again on Sunday and chanted his name. Mohammad Ali Abtahi, who served as a vice-president under Mohammad Khatami, told Reuters the former presidents brother Mohammad Reza Khatami was one of more than 100 members of Irans biggest reformist party Mosharekat who were arrested. A judiciary spokesman said the reformers were summoned and warned not to increase tension. He said they were then released. Mousavis wife, Zahra Rahnavard, denied reports that her husband himself had been detained or put under house arrest. He is following the issue of the election. He says he is with the people and beside them, said Rahnavard, who campaigned actively alongside her husband during a campaign which drew tens of thousands of supporters onto the streets of Tehran. Police said they rounded up 170 people over the protests, which triggered violence on a scale not seen since 1999 when student demonstrations led to a week of deadly nationwide unrest. 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. Interior Ministry officials have rejected accusations of fraud and Supreme Leader Ayatollah Ali Khamenei has called on Iranians to back their president. Protests also broke out on Saturday in the cities of Tabriz, Orumieh, Hamedan and Rasht, where crowds chanted for Mousavi. Though the protests were small compared to the mass demonstrations that led to the 1979 Islamic revolution, they were the most widespread in the city since then. Two Dutch journalists were also arrested and ordered to leave the country, public broadcaster Nederland 2 said. In his first Press conference since winning Fridays vote, Irans incumbent President Mahmoud Ahmadinejad said the result of the presidential election was a blow to the 'oppressive system ruling the world. In his first Press conference since winning Fridays vote, he also insisted that Tehrans controversial nuclear drive was an issue of the past. The 84 per cent-plus participation by eligible voters... is a major blow...to the oppressive system ruling the world. He said any country that dared to attack Iran would deeply regret such a move. Addressing a sea of thousands of flag-waving supporters packed into central Tehran, Ahmadinejad denied the result of Fridays 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. 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. 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, and hold more rallies. He said cancellation of the results was the only way to retain public trust and support for the government. Reformist candidate Mehdi Karroubi, who came a distant fourth with less than one per cent of the vote, said he would refuse to accept the illegitimate outcome. Meanwhile, around 200 people demonstrated outside the Iranian Embassy in London on Sunday against President Mahmoud Ahmadinejads re-election. Meanwhile, US Vice-President Joe Biden said Sunday there was an awful lot of doubt about the outcome of the Iranian elections in which President Mahmoud Ahmadinejad was declared the winner, saying Tehrans actions against dissent suggest the results may not be clear-cut. It sure looks like the way theyre suppressing speech, the way theyre suppressing crowds, the way in which people are being treated, that theres some real doubt, Biden told NBCs Meet the Press, refraining from recognising Ahmadinejad as the winner. Seventy per cent of the vote comes out of the city, thats not Ahmadinejads strong place, Biden said. The idea he gets 68 or whatever per cent of the vote in a circumstance like that seems unlikely. I have doubts but were going to withhold comment until we have a thorough review of the whole process and (see) how they react in the aftermath, he said. Thats what theyre announcing. We have to accept that for the time being. But theres an awful lot of question about how this election was run, Biden said. We are waiting to see. We dont have enough facts to make a firm judgment, he cautioned. But Biden suggested that a contested result would not keep Washington from pursuing talks with Tehran, no matter who emerges victorious in the presidential elections. Talks with Iran are not a reward for good behaviour. They are only a consequence if the President makes a judgment its in the best interest of the US to talk with the Iranian regime. Our interests are the same before the election as after the election, and that is we want them to cease from seeking a nuclear weapon and having one in his possession and secondly to stop supporting terror, he said. We are ready to talk, Biden said.