Gunman says youngsters shot on Utøya were not 'non-political children' and compares them to the Hitler Youth

Anders Behring Breivik has described his killing spree last summer as "the most sophisticated and spectacular political attack committed in Europe since the second world war".

The 33-year-old made the claims in a written statement he was allowed to read to the court on the second day of his trial – an unusual demand granted only because he refused to give evidence conventionally otherwise.

The rambling text, which he claimed he had "self censored" out of respect for the bereaved sitting in court, attempted to justify what he had done in the name of "revolutionary nationalism".

He expressed no regret for planning and carrying out the attacks that left 77 dead last summer. Maintaining he acted out of "goodness, not evil" to prevent a "major civil war", Breivik insisted: "I would have done it again."

He identified as his enemy the "cultural Marxists" who he said had destroyed Norway by using it as "a dumping ground for the surplus births of the third world". Claiming Norwegians would be a minority in their own capital "within five years", he blamed liberal politicians for bringing about Norway's demise with "feminism, quotas … transforming the church, schools".

The 69 people, many of them teenagers, who died on the island of Utøya when he opened fire on the youth camp of the ruling Labour party were "not innocent", he claimed.

"They were not innocent, non-political children; these were young people who worked to actively uphold multicultural values. Many people had leading positions in the leading Labour party youth wing," he said, going on to compare the Labour party's youth wing (AUF) with the Hitler Youth.

He quoted from a variety of sources to support his case, including, he said, a story written in the Times in February 2010 which he said reported that "three out of five Englishmen believe that the UK has turned into a dysfunctional society as a result of multiculturalism". The Guardian was unable to find evidence of such an article.

Breivik told the court that "ridiculous" lies had been told about him, rattling off a list which accused him of being a narcissist who was obsessed with the red jumper he wore to his first court hearing, of having a "bacterial phobia", "an incestuous relationship with my mother", "of being a child killer despite no one who died on Utøya being under 14".

He was not insane, he repeated many times. He claimed it was Norway's politicians who should be locked up in the sort of mental institution in which he can expect to spend the rest of his life if the court declares him criminally insane at the end of the 10-week trial.

Breivik said: "They expect us to applaud our ethnic and cultural doom … They should be characterised as insane, not me. Why is this the real insanity? This is the real insanity because it is not rational to work to deconstruct one's own ethnic group, culture and religion."

Breivik insisted he was not alone in fighting against "mass immigration". He singled out as examples the National Socialist Underground, the neo-Nazi terror cell responsible for killing nine immigrants and one policewoman in Germany, and Peter Mangs, the man suspected of carrying out a seven-year killing spree in the Swedish city of Malmö.

He said that these "heroic young people" should be celebrated for sacrificing their lives for the conservative revolution. He said that "the three most powerful politicians in Europe" shared his views, saying: "Sarkozy, Merkel and Cameron have all noted that multiculturalism doesn't work."

At the start of Tuesday's court session, one of the five judges was dismissed from the panel after it emerged he had posted a message on Facebook last year saying the "death penalty is the only just thing to do in this case". Thomas Indebro, 33, one of three ordinary Norwegians sitting as a "lay judge" alongside two professionals, stepped down and was replaced.

Breivik has five days to explain why he set off a bomb in Oslo's government district, killing eight, and then gunned down 69 on Utøya. He denies criminal guilt, saying he was acting out of "necessity". On Tuesday the court-appointed interpreters issued a correction to their translation of Breivik's not guilty plea on Monday.

He is not claiming to have acted out of "self defence", as originally reported, but using a defence under section 47 of the Norwegian penal code, which states: "No person may be punished for any act that he has committed in order to save someone's person or property from an otherwise unavoidable danger when the circumstances justified him in regarding this danger as particularly significant in relation to the damage that might be caused by his act."