A man was tonight fighting for his life after stumbling into a probation centre with a stab wound to his stomach.

Police are appealing for witnesses after the 50-year-old arrived bleeding at Oxford Probation Service, in Oxford Road, Cowley, at 1.40pm today.

He claimed he was wounded after falling off his bike.

The man had a single puncture wound to his abdomen and police and paramedics now believe he was stabbed.

He was tonight undergoing surgery at the John Radcliffe Hospital, where his condition was described as life-threatening.

Det Insp Simon Morton, of Oxford CID, said: “Just after 1.40pm the man went into the offices claiming to have fallen from his bicycle but it soon became apparent that he had been stabbed.

“We are still in the very early stages of the investigation and are keeping an open mind as to how this happened, and are asking for help from the public.

“We need to know where this man was before he arrived at the probation service and how he received the injury.”

The injured man is described as black and aged in his early 50s, with black shoulder-length dreadlocks.

He was wearing black jeans, a blue top and tan walking boots, and had a silver and black mountain bike.

Police closed the probation centre and taped off the area while forensic teams scoured the scene.

Fiona Tarrant, spokesman for Thames Valley Probation Service, said no staff were injured.

Anyone with information should call police on 08458 505505 or Crimestoppers on 0800 555111.