Oslo, Apr 5 (IANS/RIA Novosti): Norwegian gunman Anders Behring Breivik, charged with killing over 70 people in twin attacks in Oslo and a nearby youth camp last year, has written a letter to the media claiming he is mentally sound.

"Finding me insane is the worst thing to happen. It's extreme humiliation to me," the Verdens Gang newspaper cited an excerpt of Breivik's 38-page letter on its website.

The 33-year-old Breivik said he plans to push for a new examination to find him sane to be tried for the terrorist attacks.

He said the first report by psychiatrists contains 200 erroneous statements.

Breivik is on trial for killing 77 people in the dual attack last July. The majority of victims were participants at a youth camp, while eight others were killed in a car bomb blast in Oslo, staged as a diversion.

The conclusions of a psychiatric examination are to be made public April 10.

The charges carry a penalty of up to 21 years in prison, the maximum possible punishment in Norway. Breivik's prison term can be extended for as long as he is considered a danger to society. Should he be found criminally insane, he would face confinement in a psychiatric ward instead of imprisonment.

Breivik admitted to the killings, but did not plead guilty. He said his actions were a justified protest against globalisation and the advance of Islam in Europe.

He claimed he was on a crusade against multi-culturalism and the "Muslim invasion" of Europe when he carried out the attacks.