• Man found dead in sports bag in bath of London townhouse • Body was decomposing and had been stabbed, reports say

This article is more than 10 years old

This article is more than 10 years old

An MI6 worker whose body was found stuffed into a sports bag in the bath of his London flat has been identified locally today as Gareth Williams, a 31-year-old Foreign Office employee.

A post-mortem examination is being conducted amid reports that the man had been stabbed several times and was in a state of decomposition when found by police.

Reports suggest he had worked at GCHQ, the government's secret listening service in Cheltenham, and had been on secondment to MI6, the secret intelligence service. It is thought he could have been dead for as long as two weeks.

This morning, the man's former landlady, Jenny Elliott, said that he had lived in a flat in her house near Cheltenham for 10 years while working nearby.

On Monday night, she said, a woman identifying herself as the Foreign Office's head of employee assistance had knocked at her door to ask if she had heard from him lately or knew where he was.

Police found his body on Monday afternoon when they were called to his flat in Pimlico after reports that he had not been seen for some time. Inside the property, officers found the man's mobile phone and a collection of sim cards laid out, the Daily Mail reported.

The location of the five-storey townhouse, just a mile from MI6 headquarters, fuelled speculation that the man was working there before his death.

Elliott, 71, said the man had been due to move back in to her house next week after spending a year living and working in London.

"He was due to come back to me on 3 September," said Elliott. "He rang me and said he would be back then. He said, 'Can I come back?' and I said sure. I hadn't heard anything else until a lady from the Foreign Office called at six o'clock to say that they hadn't had a sighting or a whereabouts and had we heard anything."

Elliott said he was a quiet man who enjoyed cycling and running and kept himself to himself.

She added: "This awful thing is happening and he was a lovely man, very well-mannered and very likeable. He was very clever and had been to Cambridge and had a very important job at the Foreign Office. Although he didn't belong to me, I was quite proud of him. It's like losing one of my own children."

Sources close to the investigation said it was "early days" and the cause of death remained unclear.

The source added: "The suggestion there is terrorism or national security links to this case is pretty low down the list of probabilities."

A GCHQ spokesman said: "There is an ongoing police investigation and it would not be appropriate for us to comment at all as this is ongoing.

"We have nothing to add. Our policy is not to comment on individual members of staff or whether they are staff."

A police source stressed that the man had not been formally identified, saying that while his employment documentation suggested he had indeed worked for the secret service, "he might have been an air conditioning technician rather than a spy".

He added: "If he really was a spy, you imagine someone would have reported him missing rather sooner."

Scotland Yard has launched a murder inquiry, in conjunction with counterterrorist and security service officials.

The street was cordoned off last night as forensic teams searched the property and surrounding areas for clues as to how and why the man was killed.

A black private ambulance parked outside the house just before 9.30pm. A few minutes later, forensics officers, accompanied by police officers, removed the corpse in a red body bag.

A spokesman for the Metropolitan police said: "Detectives are investigating a suspicious death following the discovery of the body of a man in a central London flat. At around 1640 hours on Monday 23 August, officers attended the flat, on the top floor of a property in Alderney Street, Westminster, following reports that the occupant had not been seen for some time.

"Officers gained entry and found the body of the man, believed to be aged in his 30s. He was pronounced dead at the scene.

Scotland Yard refused to comment on the dead man's identity until next of kind had been informed. A spokesman said the post-mortem examination was still under way and could go on "for some time".

No arrests have been made.

The street of Georgian terraced homes remained cordoned off this morning and police officers stood outside No 36, which is divided into three flats.

Curtains were drawn in the top-floor flat, where it was believed the murder took place.

Many politicians and bankers live on the street, neighbours said.

One local resident said police had told her that the man could have been murdered a fortnight ago.

Land Registry documents reveal that the block is owned by a private company, New Rodina.

Its details are hidden because it is registered in the British Virgin Islands and is not listed with Companies House.

The word rodina means "motherland" in Russian and Bulgarian.

If reports of the deceased man being a spy are true, the murder will be the highest-profile one in the UK of someone linked to the secret services since that of Alexander Litvinenko.

The former KGB agent died in hospital after being poisoned by radioactive polonium-210 in 2006.