TEHRAN: An Iranian opposition leader has claimed that women and boys detained over the wave of unrest that swept the nation after the disputed presidential election have been brutally raped in custody.

The allegations by defeated presidential candidate Mehdi Karroubi surfaced as Iran hit back at Western criticism of its mass trials of protesters, including British and French embassy staff.

"A number of detainees have said that some female detainees have been raped savagely. Young boys held in detention have also been savagely raped," Karroubi said in a letter to powerful cleric and ex-president Akbar Hashemi Rafsanjani.

"The young boys are suffering from depression and serious physical and mental damage since their rapes," he said, urging a probe into the claims.

Karroubi made the allegations in a "confidential letter" delivered on July 29 to Rafsanjani in his capacity as head of the Assembly of Experts, the powerful body which selects the supreme leader and supervises his activities.

Karroubi, a reformist former parliamentary speaker who came a distant fourth in the June 12 election that returned President Mahmoud Ahmadinejad to power, has previously alleged that protesters were being abused and beaten in custody.

About 2,000 opposition supporters were arrested in the aftermath of Ahmadinejad's disputed victory. Most have been released, but around 200 remain behind bars. At least 110 have also been put on trial.

Karroubi urged Rafsanjani to take up the issue with supreme leader Ayatollah Ali Khamenei, saying the "clergy and the Islamic republic will be held responsible" for such acts.

"The people who told me about this hold sensitive positions and some are veterans of the war (with Iraq)," he said in the letter, a copy of which was obtained by AFP.

On Sunday, the head of the Revolutionary Guards' political bureau called for Karroubi, fellow defeated election challenger Mir Hossein Mousavi and Ahmadinejad's predecessor Mohammad Khatami to go on trial for plotting a "velvet coup." Iranian opposition leaders have repeatedly accused security forces of mistreating detained protesters as they maintain a defiant campaign against Ahmadinejad's victory in what they say was a rigged election.

Last month Khamenei ordered the closure of one detention centre, saying it was not "up to required standards." Several reformist newspapers have also reported that several protesters have died in custody, but officials say they succumbed to disease and denied they were beaten.

The crackdowns have outraged the international community as Iran continues to battle its worst crisis since the 1979 Islamic revolution, with deep rifts between the country's clerical groups and the ruling elite.

But Tehran hit back on Monday after Washington branded the court proceedings against protesters as "show trials." Iranian foreign ministry spokesman Hassan Ghashghavi described the Western criticism as "illegal and surprising," and said the court testimony by Iranian employees of foreign embassies was proof of foreign meddling.

"The comments made by Iranians working here is an example of foreign intervention in Iran's domestic affairs. We will strongly stand against any intervention," he said, the IRNA news agency reported.

Those on trial include French woman lecturer Clotilde Reiss, British embassy analyst Hossein Rassam and French embassy employee Nazak Afshar.

Ghashghavi denied that the court testimony given by Rassam on Saturday, who has now been charged with spying, was made under pressure.

"Rassam was already freed before he appeared in court. He was at home. He was under no pressure," Ghashghavi said at his weekly press conference.