Planned rallies to mark the one-year anniversary of protests in Tehran and other cities which resulted in at least two people dead, dozens injured, and hundreds detained when security forces brutally halted demonstrations supporting Egypt and Tunisia uprisings have been met with a crackdown, Amnesty International said.

Authorities have already mounted a crackdown on opposition protesters and temporarily cut off access to foreign email services such as Gmail, Yahoo mail and Hotmail after an Iranian opposition coalition - the Coordination Council for the Green Path of Hope, widely known as the Green Movement, urged Iranians to silently march and protest on 14 February.

Many writers, bloggers and social commentators have also been arrested in recent weeks.

On 17 January, Iranian authorities arrested the sister of an employee of BBC Persian - the BBC’s Persian language news service - and held her in solitary confinement in Tehran’s Evin Prison, apparently to try to pressure her sister abroad. Though she was eventually released on bail, she was forced to “confess” on camera.

The BBC says that family members of BBC Persian staff have had their passports confiscated, preventing them from leaving the country.

According to Iran’s state-licensed Mehr news agency, last week several people were also detained for alleged links to the BBC's Persian service. BBC Persian programmes are sometimes jammed in Iran.

The Mehr report said they were involved in newsgathering, recruiting and training for Iranian journalists and had organized trips abroad for them.

BBC Persian said it does not have any staff in Iran, but added that the reports "should be of deep concern to all those who believe in a free and independent media".

Amnesty International’s Middle East and North Africa Deputy Director Ann Harrison said:

“There is a real concern that Iranian security forces may again use excessive force to quell protests across the country. The authorities must respect people’s right to freedom of assembly and allow tomorrow’s demonstrations to go ahead peacefully.”

“An already dire situation seems to be worsening, with any dissenting voices being stamped out. Anyone held simply for peacefully exercising their right to free speech should be released immediately.”

Opposition leaders Mir Hossein Mousavi and Mehdi Karroubi have been under unofficial house arrest since February 2011.

Iran has seen increasing repression of journalists, bloggers and minority groups across the country ahead of next month’s parliamentary elections.

A wave of arrests targeting members of Iran’s ethnic and religious minorities, journalists, and
individuals with alleged links to foreign media appears to be part of a strategy to restrict free
public debate and to warn people not to protest ahead of the elections.

Some 49 members of the Ahwazi Arab minority have reportedly been arrested since 10 January this year, in at least three cities in the south-western province of Khuzestan.

Amnesty International is also concerned over reports of the arrest of at least 12 members of the Baha’i religious minority in the southern city of Shiraz. Over 80 Baha’is are currently imprisoned or detained on account of their faith or identity.