By Johan Ahlander and Victoria Klesty
OSLO (Reuters) - The Norwegian charged with going on a killing spree in which at least 91 people died is a former member of a populist anti-immigration party who wrote blogs attacking multiculturalism and Islam.
The suspect, detained after 84 people were gunned down at a youth camp and another 7 killed in a bomb attack on Friday, has been identified by Norwegian media as Anders Behring Breivik.
Website entries under Breivik's name criticized European policies of trying to accommodate the cultures of different ethic groups, and claimed a significant minority of young British Moslems back radical Islamic militancy.
"When did multiculturalism cease to be an ideology designed to deconstruct European culture, traditions, identity and nation-states?" said one entry, posted on February 2, 2010 on the right-wing website www.document.no.
"According to two studies, 13 percent of young British Muslims aged between 15 and 25 support al Qaeda ideology," said another entry dated February 16 last year.
Police searched an apartment in an Oslo suburb on Friday, but neighbors said the home belonged to Breivik's mother, whom they described as a nice lady.
Deputy Police Chief Roger Andresen would not speculate on the motives for what was believed to be the deadliest attack by a lone gunman anywhere in modern times. But they said the man in custody had described himself on his Facebook page as leaning toward right-wing Christianity.
Breivik had also been a member of the Progress Party, the second largest in parliament, the party's head of communications Fredrik Farber said. Breivik was a member from 2004 to 2006 and in its youth party from 1997-2006/2007.
The Progress Party wants far tighter restrictions on immigration, whereas the center-left government backs multiculturalism. The party leads some polls of public opinion.
Progress leader Siv Jensen stressed he had left the party. "He is not a member any more," she told Reuters. "It makes me very sad that he was a member at an earlier point. He was never very active and we have a hard time finding anyone who knows much about him."
Farber said: "He was a member and had some participation in the local chapter in Oslo but stopped paying his membership dues and ceased being a member in 2006 or 2007."
Breivik was also a freemason, said a spokesman for the organization. Freemasons meet in secretive fraternal groups in many parts of the world.
(Additional reporting by Patrick Lannin; editing by David Stamp)