A British man has been arrested in Germany on suspicion of spying for Russia.

German federal prosecutors said the man - named only as David S - worked at the British embassy in Berlin.

He allegedly passed documents to Russian intelligence "at least once" in exchange for an "unknown amount" of money.

He was arrested in Potsdam outside Berlin on Tuesday and his home and workplace have been searched.

A spokesman for Germany's foreign ministry quoted by AFP news agency said Berlin was taking the case "very seriously", and said spying by "a close alliance partner on German soil is unacceptable".

The arrest was the result of a joint UK-German investigation, the statement read.

It was intelligence-led and had been going on for some time leading up to the arrest, the BBC's Security Correspondent Gordon Corera says. MI5 and other UK agencies, as well as British police, had been working with the Germans to learn as much as they could about the alleged activity.

Australian police have issued a fresh appeal for help to find the remains of Peter Falconio, the British backpacker murdered in the outback 20 years ago.

The 28-year-old was shot dead when he and his girlfriend Joanne Lees were ambushed near Alice Springs in 2001. His body was never found. Australian man Bradley Murdoch was found guilty of his murder in 2005.

Despite pleas, he has refused to tell authorities where he disposed of Mr Falconio's body. The Northern Territory police renewed their search appeal on Wednesday, the 20th anniversary of Mr Falconio's disappearance.

They urged "anyone out there with any information" to come forward to police to help "assist Peter's family in gaining some sort of closure".

"We are thinking of Peter's family and friends on this anniversary and remain hopeful that such a milestone may jolt some information and progress the investigation," said Det Snr Sergeant Karl Day.