Iran's Supreme Leader Ali Khamenei has led funeral prayers for two senior judges who were killed in their offices on January 18, state media reported.

Ali Razini and Mohammad Moghiseh, characterised as prominent hardline members of Iran's judiciary, were commemorated at a ceremony in Tehran's Imam Khomeini Hussainiya later on January 19.

Speaking to the families after the prayers, Khamenei praised both men. "May God bestow his mercy on Mr Razini. He spent a good life, praise be to God, striving and working hard in God's path," Khamenei said, according to Mehr news agency.

Of Moghiseh, the Supreme Leader said: "May God elevate his status. He must have done some great, righteous deed in his record for God to honour him with martyrdom."

The Islamic Republic has lost several top officials from military and political factions in recent years, including President Raisi, who was a former judiciary official before his death in the summer in a helicopter crash. The targeting of the two men by a gunman who killed himself after the assassination is the newest form of targeting of the Islamic system.

Khamenei told the bereaved families that both judges "had made great efforts and undertaken major work throughout their lives, which made them deserving of divine reward and martyrdom in God's path."

The shooting occurred at Iran's Supreme Court in Tehran when the unnamed 31-year-old janitor entered Chamber 39 around 10:30 local time, drew a concealed weapon, and opened fire, killing Razini and Moghiseh. A security guard was also wounded in the shoulder during the attack.

According to criminal investigators, the assailant fired six shots in rapid succession before fleeing to the building's third floor, where he fatally shot himself in the heart. The entire attack in the judges' chamber lasted just 13 seconds, police said.

"A militant infiltrator at the Supreme Court, in a planned action, assassinated two brave and experienced judges who fought against crimes against national security, spies and terrorism," the judiciary said in a statement.

The attacker, who had worked at the court system for 10 years, had no previous disputes with the victims, investigators said. His motives remain unclear, as he took his own life before he could be questioned.

Several court employees and security guards have been detained as part of the investigation, according to an informed source. Iran's Prosecutor General Movahedi has ordered Tehran's prosecutor to handle the case swiftly and identify any potential accomplices.

Witnesses reported hearing the gunshots and rushing to Chamber 39, where they found the judges bleeding and immediately called emergency services. Three ambulances were dispatched to the scene, but both judges were pronounced dead. 

Local journalist Neda Khodayari reported initially that the attacker obtained a service weapon belonging to the court guard after wounding him.

Iran’s Supreme Court is the highest judicial authority in the country, overseeing appeals and key legal decisions.

The attack has raised concerns about security at the nation’s top judicial institutions with security now increased across courts in the country.