The trial of alleged members of the Islamic State group (IS) who took part in an attack in Tehran in 2017 began on Saturday in the country's Revolutionary Court.

The case involves 26 defendants. Eight attended the first hearing with their lawyers.

Charges include being members of a terrorist organisation, weapons possession and unauthorised entry into the country.

According to his indictment, a suspect identified only with his initials 'S.M.' left the country in 2015 and joined IS.

In 2016, he re-entered to the country wearing a suicide belt and carrying weapons.

In June 2017, five militants linked to IS stormed Iran's parliament and a shrine to revolutionary leader Ayatollah Khomeini, killing at least 18 people and wounding more than 50.