By Walter Gibbs

OSLO (Reuters) - Anders Behring Breivik, who has confessed to the bomb and shooting attacks that killed 77 people in Norway in July, says there are up to 80 cells in Europe with militant anti-Islamic ideals like his own, Norwegian investigators said on Thursday.

Norwegian police said previously that Breivik had said there were two or three cells in Norway, apart from himself, and "several" elsewhere in Europe that shared his plans to stop what they saw as an Islamic invasion of Europe.

"It's more like three in Norway and 80 around Europe," police prosecutor Christian Hatlo told Reuters, adding that Breivik had made the allegation since shortly after his arrest on July 22.

Hatlo added: "We have not uncovered a single one of them."

He said the police had intentionally played down Breivik's alleging of 80 like-minded cells in order to avoid causing panic across the continent at the time.

Police spokesman Roar Hansen, who has briefed reporters since the attacks, confirmed the number.

"The number I now have is between 60 and 80," he said. "But I don't think they (investigators) trust what Breivik is saying on this matter."

Hatlo said Norwegian police had asked authorities in 20 nations to interview 35 non-Norwegians in connection with the July 22 killings caused by a bomb in Oslo and a gun massacre at a nearby island summer camp for Labor Party youths.

Fifteen of the 35 remain to be interviewed, he said, though none is considered a potential accomplice.

He said the purpose of the international inquiries was to document Breivik's travels, purchases and ideological alliances.

"We still think he (Breivik) did this alone and we have not uncovered any accomplices. But it is far too early to draw any final conclusions," Hatlo said.

At a news conference on Thursday Hatlo said investigators had recovered 186 shell casings from the island where Breivik attacked the summer camp, killing 69 of his 77 victims.