TEHRAN - An Iranian opposition leader has been jailed for six years for his role in the unrest following June's disputed presidential election, reports say.

Mohsen Aminzadeh was convicted of organising protests, disturbing security and spreading propaganda against the system, his lawyer said.

He was a prominent supporter of the defeated candidate Mir Hossein Mousavi.

Meanwhile, opposition websites say nine journalists have been detained in the past two days, taking the total to 55.

There has so far been no confirmation from the Iranian government.

Correspondents say the authorities are tense ahead of the 31st anniversary of the Islamic Revolution on Thursday.

Opposition supporters have called for widespread anti-government protests to coincide with official rallies. The police have meanwhile warned that opposition demonstrations will be firmly confronted.

In December, eight people were killed in clashes at demonstrations on Ashura, one of the holiest days in the Shia Muslim calendar.

In a joint statement, the US and the European Union expressed concern about "continuing human rights violations in Iran" since the election and about the possibility of further violence as the revolution's anniversary is marked.

"The large scale detentions and mass trials, the threatened execution of protesters, the intimidation of family members of those detained and the continuing denial to its citizens of the right to peaceful expression are contrary to human rights norms," the statement said.

Speaking to the semi-official Isna news agency on Monday, Mr Aminzadeh's lawyer said his client had been sentenced to six years in prison by a branch of the Revolutionary Court in Tehran.