As a result of the attack, and two further robberies in the same week, police have stepped up patrols in the area.

Vladimire Filalejeus was attacked by two men with a blunt instrument in the alleyway called Harbour Lines on Eastfield Way at around 9pm.

Cash and a mobile phone were stolen from him.

The incident left the 31-year-old with serious head injuries and he remains in a stable condition at Queen Elizabeth Hospital, King's Lynn.

Detectives have released the picture, in the hope that it will encourage anyone with information to come forward.

Yesterday, police renewed their appeal for witnesses. They confirmed a youth has been arrested on suspicion of robbery, but yesterday had not been charged.

Police have also linked the attack with another robbery that took place just over an hour later in Station Road, where two men attacked a woman and stole her rucksack at around 10.15pm.

The woman was injured, but did not require hospital treatment.

The men are described as white, around 5'8", medium build and between 18 and 20. They both spoke English.

There was another incident on Tuesday, July 29, in Eastfield Way and police have charged a 17-year-old in connection with this and another alleged incident at Creek Road, March, on the same day.

DC Emily Clarke said: "It is vital that if anyone knows who is behind these robberies they contact police immediately.

"Whilst these types of incidents do not happen very often, additional police patrols will be taking place in the area.

"The location of where the 31-year-old man was attacked is an alleyway which is locally known as The Harbour Lines, rather than its official name of Eastfield Way."

Anyone with information is asked to contact DC Clarke at Wisbech Police Station on 0845-4564564 or Crimestoppers, anonymously, on 0800-555111.