Iranian President Mahmoud Ahmadinejad defended his hotly disputed re-election win at a huge rally on Sunday after security forces cracked down on opposition protestors with mass arrests.
Sporadic violence erupted in Tehran as supporters of Amadinejad's defeated rival Mir Hossein Mousavi clashed with police for a second day following an election the opposition has charged was rigged and wants annulled.
Addressing a sea of flag-waving supporters packed into central Tehran, Ahmadinejad denied that the result of Friday's vote which has given the hardliner 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... and the psychological war launched by the enemy."
But Western nations have raised concerns about the legitimacy of the results and the crackdown on opposition supporters which followed a wave of rioting in Tehran on Saturday.
US Vice President Joe Biden there was "an awful lot of doubt" about the outcome of the vote but refrained from saying whether Washington accepted the results.
The defeated Mousavi he lodged an appeal with the powerful Guardians Council to seek the cancellation of Friday's vote and called on his supporters to continue their protests peacefully.
Analysts have warned that the dramatic events could pose a risk to the future of the Shiite-dominated country, which has been under the control of powerful clerics since the Islamic revolution three decades ago.
Police said they have rounded up a total of 170 people over the post-election protests, which triggered rioting on a scale not seen in Iran for a decade.
Tehran's deputy police chief Ahmad Reza Radan those arrested included "masterminds" of the rioting as well as politicians and warned that the security forces would deal "firmly" with the protests.
In one street on Sunday, police fired into the air to break up a demonstration, while on another, about 200 Mousavi supporters shouting "Death to the dictator!" lobbed stones at police who fired back with tear gas.
Among those arrested by police were around 15 reformist leaders and supporters of Ahmadinejad's defeated rivals who complained of fraud in the most hotly-contested presidential election in the Islamic republic.
The election results dashed Western hopes of change after four years under the combative Ahmadinejad, who set Iran on a collision course with the international community over its nuclear drive and his anti-Israeli tirades.
One leading conservative in Tehran insisted that US President Barack Obama's "motto of change" and "velvet revolutions" had no place in Iran.
Official results gave 52-year-old Ahmadinejad 63 per cent of the vote, crushing his closest rival Mousavi who gained just 34 per cent.
Reformist sources said those arrested also included several people who served under two-time reformist president Mohmmad Khatami, including his brother, and supporters of former parliament speaker Karroubi.
Several have since been released, reformist sources said.
Iranian authorities said all unauthorised demonstrations were banned, and even before Friday's election the elite Revolutionary Guards had warned it would put down any "velvet revolution."
Iran's all-powerful supreme leader Ayatollah Ali Khamenei, who has the final say on all matters of state including foreign and nuclear policy, urged the country to unite behind Ahmadinejad.
The election campaign, with its mudslinging candidate debates and mass street rallies, appears to have galvanised a grass-roots push for change in a country where 60 per cent of the population was born after 1979.
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.
But Mehdi Chamran, the head of Tehran city council and a prominent conservative, said Obama's "motto of change" had no place in Iran.
"Iran's identity does not allow a blind imitation... velvet and coloured revolutions do not work among our people," he said in the Hamshahri newspaper.
Obama has reached out to the Muslim world and called for dialogue with Iran after three decades of severed ties, a break from the approach of his predecessor George W Bush who once labelled Iran part of an "axis of evil."
In Washington, analysts warned that Ahmadinejad's return would complicate efforts to resolve the standoff over Iran's nuclear drive, which Ahmadinejad said on Sunday was "history".
The West fears it is a cover for ambitions to build atomic weapons but Tehran insists it is for peaceful purposes only and has defied international demands to halt uranium enrichment despite UN sanctions.
Israel voiced concern over the return of Ahmadinejad, who has caused international outrage by describing the Holocaust as a myth and calling for the Jewish state to be wiped off the map.