TEHRAN: Iranian President Mahmoud Ahmadinejad today defended his hotly disputed re-election as security forces cracked down on opposition protesters in Tehran, where fresh violence erupted.

Police said they have rounded up a total of 170 people over the massive post-election protests and street riots which erupted in the Iranian capital after Ahmadinejad’s defeated challengers complained of fraud and vote-rigging.

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. But Ahmadinejad dismissed criticism of the election, saying at a press conference the massive turnout was a blow to the “oppressive system ruling the world,” a reference to Iran’s arch-foe the United States.

He said his margin of victory over his main rival, moderate ex-premier Mir Hossein Mousavi, was so wide it could not be questioned and said the election was like a “football match” and the loser should just “let it go.” But clashes flared again today, a day after thousands of angry opposition supporters took to the streets over the election result, triggering rioting on a scale not seen in Iran for a decade. In one street, 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.

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.

Official results gave 52-year-old Ahmadinejad 63 percent of the vote, crushing his closest rival Mousavi who gained just 34 percent.

But Mousavi, who has not been seen in public since the vote results cried foul over what he branded a “charade,” saying it was marred by cheating and election irregularities.

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.