Tehran - Supporters of incumbent Iranian President Mahmoud Ahmadinejad and his main electoral challenger Mir-Hossein Moussavi clashed on Friday in Tehran, just one week ahead of June 12 presidential elections.

A thousand Moussavi supporters were holding a rally in Tehran's Vali-Asr square when suddenly the same number of presidential supporters staged a counter rally, eyewitnesses said.

After initial verbal quarrels between the groups, the supporters of both sides started clashes and police forces immediately interfered to prevent an escalation of the confrontations.

Spontaneous street demonstrations in other parts of the capital with small verbal and physical quarrels between the two sides were also reported by eyewitnesses.

The street demonstrations began Wednesday following a heated live debate between the two rivals on state-run television watched by tens of millions of Iranians.

For the first time since the 1979 Iranian revolution, a candidate harshly attacked the policies of an incumbent president and the president accused his predecessors of lies and corruption.

While Moussavi charged Ahmadinejad with humiliating the Iranians before the world, the president accused his predecessor Mohammad Khatami of having lied to the people about his PhD degree and ex- president Akbar Hashemi-Rafsanjani and his family of having been corrupt.

In a speech on Friday in Bojnourd, north-eastern Iran, Moussavi told his supporters that the country has gone backward, rather than forwards since Ahmadinejad's presidency began in 2005.

"We are fed up with this and want to save the country from this backwardness," the labour news agency ILNA quoted Moussavi as saying.

"We are fed up with lies and want to save Iran from these lies," added Moussavi while referring to governmental economic statistics whose accuracy is doubted by the country's opposition parties.

Moussavi harshly criticized the president's economic plans, saying a 25-per-cent inflation rate meant reducing one quarter of the people's purchasing power and would not be in line with the president's economic reform claims.

According to opinion polls, whose sources are however not fully reliable, Ahmadinejad is still leading but Moussavi has caught up and increased the gap to a minimum.(dpa)