British police were Tuesday examining possible links between Norwegian terrorism suspect Anders Behring Breivik and right-wing extremists in Britain, Prime Minister David Cameron confirmed.
In a 1,500 page manifesto posted online shortly before Friday's twin attacks in Norway, Breivik claimed he had been recruited to radical causes by two English right-wing extremists at a meeting in Britain in 2002.
Cameron said no details would be given out while the claim was still being investigated but said it was being taken "extremely seriously." Foreign Secretary William Hague confirmed that a British police officer was helping Norwegian investigators.
Breivik, who confessed to having carried out the bombing in Oslo and the shootings at Utoya Island Labour Party youth camp in which a total of 76 people were killed, said Monday at a custody hearing there two more cells in his organization.
According to Breivik's manifesto which he signed with an anglicized version of his name, Andrew Berwick, and datelined London 2011, he had 600 members of the far-right English Defence League (EDL) as Facebook friends and had had contact with the group's leaders.
An organizer of EDL demonstrations, Darly Hobson, also said Breivik had met members of the group, according to the Daily Telegraph newspaper.
One senior EDL member said the Norwegian had had a "hypnotic" effect on them, while another told the paper he believed Breivik had met EDL leaders when he came to London last year to hear Dutch right-wing politician Geert Wilders speak.
The EDL has distanced itself from Breivik.
"There has never been any official contact between him and the EDL," the group said in a statement posted on its website.
"Our Facebook page had 100,000 supporters and receives tens of thousands of comments each day. And there is no evidence that Breivik was ever one of those 100,000 supporters," the group said.
In an interview with the BBC, EDL leader Stephen Lennon denied knowing Hobson, said he had never met Breivik, and did not believe he had taken part in EDL demonstrations.
In his manifesto, Breivik decribed the EDL as "naive fools," Lennon said, adding: "We stand against extremism and we condemn all acts of violence.
"But at the same time you have to give people in our community that are concerned about the threat of Islam, which is a genuine threat, you have to give them an opportunity to have a voice," he said.
Cameron, who signed a book of condolence at the Norwegian embassy on Monday, said Britain would review its own security in light of the attacks.
"Britain has already provided police assistance and will continue to offer our expertise and our moral support," he added.
"Britain and Norway have been good allies and neighbours in very dark days before. We know that the resilience and the courage and the decency of our Norwegian friends will overcome this evil," he said.