A trial began on Saturday of 16 opposition protesters charged over unrest connected with Iran's disputed June presidential election, with the Revolutionary Guards warning against further demonstrations.
Five of the defendants were charged with the capital offence of "moharebeh" (waging war against God) while the remainder were accused of public order and national security offences, a court website said.
All of the accused were arrested after eight people were killed in clashes between opposition supporters and security forces on Ashura, the holy Shiite day of ritual mourning, that fell on Dec. 27. The date coincided with the seventh day of mourning for leading dissident cleric Grand Ayatollah Hossein Ali Montazeri.
Iran's Islamic Revolutionary Guards (IRGC) on Saturday warned opposition groups not to stage protests on Feb. 11, the anniversary of the 1979 revolution that created the Islamic republic.
Opposition websites have been inviting people to stage more anti-government rallies on the day.
Widespread protests that followed almost immediately after the June 2009 election plunged Iran into its deepest internal crisis since the overthrow of the Shah.
"Under no conditions will we let the 'green movement' show up ... Certainly, we won't witness such a thing and even if a minority wants to do something, it will be firmly confronted by us," Brigadier General Hossein Hamedani, commander of Tehran Revolutionary Guards, was quoted as saying on semi-official news agency ISNA.
Green was the colour adopted by the supporters of Mirhossein Mousavi, who unsuccessfully challenged hardliner Mahmoud Ahmadeinjad in the June 2009 presidential election. It was later taken up by the wider opposition movement.
On Friday a conservative cleric urged the judicial authorities to execute more opposition protesters.
The semi-official Isna news agency quoted the deputy Tehran prosecutor as saying that of the 16, one was a member of the outlawed Baha'i faith, one was a communist and some of the rest belonged to the counterrevolutionary group Mojahedin Khalq Organization.
Semi-official Fars news agency reported an additional 150 people had been detained over the Ashura unrest, taking the total number of opposition protestors arrested in the aftermath of the Dec. 27 protest to more than 450, according to officials.
On Thursday Iran hanged two men convicted of moharebeh over the unrest.
Mousavi and Mehdi Karoubi -- who also contested the election -- condemned the hangings, saying the men had been arrested before the election, and called for Feb. 11 protests, website Sahamnews said.
"It seems that the purpose of such an action was to intimidate people so they will stay away from Feb. 11 rallies," the site quoted them as saying in a statement.
Fars also said security forces had obtained films and photographs from the 150 people detained which will help the identification of and arrests of "a large number of additional rioters."