Stian Lysberg Solum / AP

Anders Behring Breivik stands between two police officers prior to taking his seat after a break in the courtroom in Oslo on May 15, 2012.

A man set himself on fire and tried to force his way into the Norwegian courthouse where far-right mass killer Anders Behring Breivik is on trial for massacring 77 people last July, police said on Tuesday.

The man, who appeared to be a white Norwegian in his 50s, doused himself with liquid and set himself on fire before shouting at police officers and rushing toward a gate in the security perimeter, witnesses and police said. There was no indication of a motive.

Breivik has been on trial in Oslo since last month for killing eight people with a car bomb, then shooting dead 69 more, most of them teenagers, at a Labour Party island summer camp in protest against immigration and multiculturalism.

Although reaction to the trial has been mostly calm, days of harrowing testimony from survivors of Norway's worst peacetime massacre have raised the tension, and last week the brother of a man gunned down by Breivik hurled a shoe at him in court.

Tears as victim's brother throws shoe at Norway mass killer Anders Breivik

Witnesses quoted by the news agency NRK said the burning man had shouted "Shoot me! Shoot me!" before he was tackled by police, who poured water over him.

However, a journalist at the scene said he may have shouted "Put me out!", which sounds similar in Norwegian.

Police spokesman Kjell Kverme said the man, who appeared to be a Caucasian Norwegian, had been taken to the hospital with serious injuries to his torso.

A video of the incident posted by the daily newspaper VG on its website shows the man, with flames coming from his hat and sweatshirt, walking toward the barrier and shouting at officers.

He then turns and rushes toward the security checkpoint, where heavily armed officers wrestle him to the ground and rip his burning clothes off.

Slideshow: Norway in mourning after massacre

Moshen Nouni, who works at a kebab shop across from the courthouse, said water had been poured on the man before he was rushed to hospital.

Inside the courtroom, witnesses continued to describe how Breivik hunted down his victims on Utoya island, often taking them down with the first shot then finishing them off with a shot to the head.

Breivik admits carrying out the killings but has said they were necessary to protect Norway against "traitors" who deserved death for embracing left-wing values including immigration and multiculturalism.

He has said he should either be executed or acquitted, calling the prospect of a prison sentence "pathetic" and an insanity ruling "worse than death".

One court-appointed team of psychiatrists concluded he was psychotic while a second team came to the opposite conclusion.

If he is deemed sane, Breivik faces a 21-year jail sentence with indefinite extensions for as long as he is considered dangerous.

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