Iranian opposition leader Mirhossein Mousavi has urged his supporters not to be provoked by the detention of one of his top allies and another reformer, a statement on his website said.

Mousavi said the detention of reformers Alireza Hosseini Beheshti and Morteza Alviri was a 'sign of more horrendous events to come'.

'Keep your calm and remain aware,' said Mousavi in the statement posted on the website Kaleme.com. 'Be careful not to let them (authorities) provoke you'

The arrests on Tuesday, reported by reformist websites, signalled increasing pressure by the authorities on pro-reform foes of President Mahmoud Ahmadinejad.

Ahmadinejad renewed his defence of the disputed June election, saying on Wednesday his re-election was a defeat for the West which he accused of meddling in the polls.

'The ... presidential election was a historic slap in the face of the shaky liberal democracy,' the state news agency IRNA quoted Ahmadinejad as saying.

Mousavi's website earlier quoted the wife of Beheshti, who heads an opposition committee looking into alleged abuse of imprisoned protesters after the disputed June election, as saying he was arrested in his home on Tuesday.

The wife, who was not named, said five security agents took part in the raid and searched 'everywhere, even the bedroom' for several hours and seized personal belongings and documents before taking Beheshti away.

The family was treated in an 'impolite way,' she added.

Arrests

He is the son of Ayatollah Mohammad Hosseini Beheshti, who was head of Iran's supreme court for about a year after its 1979 Islamic revolution and killed in a 1981 bombing attack.

There was no immediate comment from officials on the report.

Another reformist website, mowjcamp.com, said on Tuesday that Alviri, a top aide of pro-reform cleric Mehdi Karoubi and a former Tehran mayor, had been detained.

Also on Tuesday, judiciary officials closed down Karoubi's office in northern Tehran and seized documents and computer data disks, the ILNA news agency reported earlier.

Beheshti has issued estimates of the number of people killed in post-election unrest that are much higher than the official death toll of around 26 people. The opposition says more than 70 people died during street protests after the vote.

The European Union expressed its concern over the closure of Karoubi's office and arrests of his and Mousavi's staff members.

'This would appear to be a concerted  effort by the government of the Islamic Republic of Iran to quiet peaceful opposition and stop the dissemination of information regarding the situation of persons imprisoned after the elections in Iran,' EU presidency holder Sweden said in a statement.

Mousavi and Karoubi, who finished second and fourth respectively in the election, say the poll was rigged to secure Ahmadinejad's re-election. The authorities deny the charge.

The hardline president shored up his position last week when parliament approved most of his new ministers, after almost three months of political turmoil in the major oil exporter.

Karoubi, whose newspaper was closed down three weeks ago, angered hardliners in August by saying some jailed protesters were raped and abused in jail. Authorities denied it, while the judiciary and parliament have agreed to look into the issue.

The election and its turbulent aftermath plunged Iran into deep internal crisis. Rights groups say thousands of people, including senior pro-reform figures, were arrested after the poll, though most have been freed. – Reuters