Ayatollah Ahmad Khatami delivers Friday prayer sermon, at Tehran University campus, 26 Jun 2009

A senior Iranian cleric has called on the government to punish the leaders of the country's post-election protests cruelly and without mercy.

In a sermon at Tehran University on Friday, Ahmad Khatami described the demonstrators as rioters who wage war against God ("moharem"), a crime in Islamic law, punishable by death.

He also accused foreign journalists of instigating the protests.

The street demonstrations that took place nearly every day since the election have largely subsided due to a heavy police presence.

But on Friday groups of Iranians visited a Tehran cemetery to pay tribute to a young woman named Neda (Aghad Soltan).  The opposition says she was killed by Iranian security forces during the demonstrations, and a video of her death on the street in Tehran was widely circulated.

Meanwhile, the relatives of citizens detained by authorities sent a letter to the head of Iran's judiciary, Ayatollah Shahrudi, and Parliamentary Speaker Ali Larijani,  expressing concern for the detainees' well-being.  The letter says they are concerned the detainees, who include prominent reformist politicians, are being pressured to confess to crimes.  Iranian authorities have arrested hundreds of people since the election.

On Friday, Iran's Guardian Council rejected allegations of fraud, calling the disputed June 12 presidential election the cleanest vote the country has ever had.

The official IRNA news agency said the Guardian Council found no major violations in the vote which declared incumbent President Mahmoud Ahmadinejad the winner by a large margin.

Both the Guardian Council and Iran's Supreme Leader Ayatollah Ali Khamenei have said the results will not be annulled.

Defeated presidential candidate and reformist leader Mir Hossein Mousavi vowed on Thursday to resist pressure to end his challenge of the election outcome.  He also urged supporters to continue protests in a way that will not create tension. 

With the post-election demonstrations, Iran has seen the largest unrest since the 1979 Islamic Revolution. 

Iran's crackdown has included heavy restrictions on reporting and the arrest of university professors, journalists and ordinary citizens. 

The official death toll from post-election violence is 17, but witnesses say it is much higher.  State media reported Thursday that eight members of the pro-government Basij militia also were killed.

Some information for this report was provided by AFP, AP and Reuters.