A British man, who is facing fraud charges after he "returned from the dead" five years after going missing, had grown a beard and used an assumed name to hide the fact he was still alive, police said.

John Darwin, 57, walked into a London police station last week claiming amnesia after apparently drowning at sea in a canoeing accident five years ago, sparking days of international media coverage.

Cleveland Police in northeast England issued a photo of Darwin with a straggly beard and appealed for information from anyone who might have known him under the name John Jones.

Earlier on Monday Darwin was remanded in custody until December 14 at Hartlepool Magistrates Court charged with obtaining money by deception and making a false declaration to get a passport.

Police said they had also started questioning his wife Anne, 55, who they arrested on suspicion of fraud on Sunday following her return from Panama, where she had recently moved.

Detective Superintendent Tony Hutchinson told reporters that Mrs Darwin was cooperating with police. "She's not saying 'no comment' to every question," he said.

Hutchinson said there was nothing to suggest that couple's sons were anything other than victims of the suspected deception, adding that he felt "dreadfully sorry" for them. "They have believed for the past five years their father is dead," said Hutchinson.

"Now they find out that not only is he alive, but he has been arrested. And they now find out from the newspapers that their mother knew that their father was alive."

The sons said last week they wanted no further contact with their parents after their mother told newspapers a photo of her and her husband taken together in Panama last year was genuine. Hutchinson said the motive for Darwin's reappearance and earlier disappearance remained unknown.

He said Darwin's sons could not identify any event which could have triggered the disappearance, but said police would investigate whether there were financial issues. International coverage of the case had resulted in "countless calls" to police with information about the couple as well as emails from Spain and the Caribbean, Hutchinson said. He appealed for the flow of information to continue.

"We need to know where Mr and Mrs Darwin have been both in Europe and North and South America.

"We need to know who they have been with and we need to know what they have been doing."

Anne Darwin had had reported her husband missing in 2002 when he failed to return home after canoeing in the North Sea near their home in Hartlepool, northeast England. A few weeks later the shattered remains of his red kayak were discovered. A coroner declared Darwin dead in 2003 after a police inquiry.