The grisly discovery of a missing man’s severed thumb has caused police to step up their investigation into his kidnap.

Forensic tests confirmed the body part belonged to 41-year-old Mahmood Ahmad, who was reported missing after finishing his shift in a kebab shop early on March 7.

A 39-year-old man from Croydon and three other people have been arrested in connection with the disappearance.

Police have refused to rule out the possibility of murder following the gruesome find, which was turned up by a member of the public in Ilford on March 10.

Detective Chief Inspector Melanie Burn, of Bedfordshire and Hertfordshire major crime unit, said: “We are urgently appealing for any information on Mahmood's whereabouts.

“He may well be injured and need urgent medical help.”

Anyone with information can ring the incident room in confidence on 01707 355798, or Crimestoppers anonymously on 0800 555 111.

-Mohammed Riaz, 33, of no fixed abode has been charged with kidnap, false imprisonment, harassment and burglary in connection with Mr Ahmad’s disappearance.

He has been remanded in custody and is due to appear in court on May 24.