Amnesty International has condemned the execution of two men arrested during protests that followed Iran's disputed presidential election last year.
They are the first executions known to be related to the post-election violence that erupted across Iran in June and has continued since.
"These shocking executions show that the Iranian authorities will stop at nothing to stamp out the peaceful protests that persist since the election," said Hassiba Hadj Sahraoui, Amnesty International's Middle East and North Africa Deputy Director.
"These men were first unfairly convicted and now they have been unjustly killed – it is not even clear they had links to this group as their 'confessions' appear to have been made under duress."
According to the Iranian authorities, at least nine other people are currently on death row in Iran after being sentenced to death in similar post-election 'show trials'.
"Our fear is that these executions are just the beginning of a wave of executions of those tried on similar vaguely worded charges," said Hassiba Hadj Sahraoui.
Mohammad Reza Ali-Zamani and Arash Rahmanipour were convicted of “enmity against God” by Tehran's Revolutionary Court in October. They were also convicted of "propaganda against the system", "insulting the holy sanctities" and "gathering and colluding with intent to harm national internal security".
Mohammad Reza Ali-Zamani was accused of illegally visiting Iraq where he was alleged to have met US military officials.
Arash Rahmanipour's lawyer says he played no role in the election protests and was forced to confess in a “show trial” after members of his family were threatened.
The two men's lawyers were not informed of their clients' executions, as is required by Iranian law.
"These executions highlight how the justice system is used as an instrument of repression by the authorities. They are sending a warning to those who may wish to exercise their right to peacefully demonstrate against the government, not to go out in the street,” said Hassiba Hadj Sahraoui.
Further anti-government demonstrations are widely expected to take place on the anniversary of the Islamic Revolution on 11 February.
According to Iranian officials, over 40 people have died in demonstrations since the election, which were violently repressed by the security forces. Amnesty International believes the number to be much higher. More than 5,000 people have been arrested, many of whom were tortured or otherwise ill-treated.
Scores have been sentenced to prison terms, and in some cases flogging, after unfair trials, and at least 11 have been sentenced to death. One man – Hamed Rouhinejad - has had his death sentence commuted on appeal in January 2010.