The first trial of people allegedly involved in post-election violence in Iran has begun.

The charges included rioting, vandalism, "acting against national security", and conspiring against the ruling system, state media reported.

The defendants included leading members of the opposition reform movement, including a former vice-president.

Some told the court their earlier claims of fraud during the 12 June poll were baseless, official media said.

Allegations of vote-rigging were made by defeated candidates and their supporters as soon as it became clear the president had been re-elected with a massive margin.

Former vice-president Mohammad Ali Abtahi was quoted by Fars news agency as telling the court: "I say to all my friends and all friends who hear us, that the issue of fraud in Iran was a lie and was brought up to create riots."

In Saturday's trial dozens of people were on trial, with photographs from the packed courtroom showing seated defendants wearing prison uniforms and with guards next to them.

Foreign media are restricted in their coverage of events in Iran.

Official news agency Irna said other charges included "having ties with counter-revolutionary groups."

Some of those on trial had been photographed "committing the crimes", and their accomplices were "on the run", Irna reported, without specifying the number of people on trial.

The defendants included supporters of opposition leaders Mir Hossein Mousavi and Mehdi Karroubi - both defeated in the election - and aides of former reformist president Mohammad Khatami.

Fars news agency, which said 100 defendants were on trial, reported that former deputy foreign minister Mohsen Aminzadeh, former government spokesman Abdollah Ramazanzadeh, former senior lawmaker Mohsen Mirdamadi and former Industry Minister Behzad Nabavi were among the defendants.

The protests were the largest mass demonstrations seen in Iran since the 1979 revolution which brought the current Islamic regime to power.

In the days of violence following the re-election of President Mahmoud Ahmedinejad at least 30 people were killed.

Authorities also arrested hundreds during the protests.

About 140 people arrested at the time were released from prison on Tuesday, with a further 200 accused of more serious crimes remaining in prison.

Opposition groups believe the number of prisoners and those killed in the violence to be higher.

Mr Ahmadinejad is due to be officially sworn in on 5 August.

Clashes have continued since his election, most recently during mourning to mark 40 days since the death of Neda Agha Soltan who was shot as she watched protests on 20 June.

State TV said police used teargas to disperse crowds from around her grave on Thursday.