OSLO -- The trial of the man accused of conducting a deadly rampage at a gay bar in Oslo in 2022 during the city's annual Pride celebrations is set to begin on Tuesday.

Two people died, nine suffered gunshot wounds and 25 others were injured after a shooting at the London Pub, a longstanding hub of Oslo's LGBTQ+ scene, as well as a nearby bar in the centre of the Norwegian capital.

Zaniar Matapour, a 44-year-old Iranian-born Norwegian citizen, described by police as a radicalised Islamist with a history of mental illness, will stand trial on charges of committing gross terrorism and murder.

He was apprehended by revellers near the scene within minutes of the attack. Police arrived shortly after.

Lawyers have not said how Matapour will plead.

According to the charges against him, Matapour started shooting at about 0113 local-time (0013 GMT), some 50 minutes after swearing allegiance to the Islamic State.

"He shot with weapons against individuals who were outside the ... venues and against individuals who tried to hide or run away," said the charges.

If found guilty, he could be serving a prison sentence of up to 30 years. He could also be detained indefinitely, if he is deemed to pose a continuing risk to society.

But the court must also determine whether he was sane at the time of the attack, or suffering from mental disorders so severe that he could not be held criminally responsible. In the latter case, he would be likely to be detained in a psychiatric facility.

An independent inquiry into the authorities' response concluded in 2023 that police could have prevented the attack had they acted on a tip-off from the foreign intelligence agency.

The trial is scheduled to run until mid-May.