A knife-wielding heroin addict is terrorising shopkeepers for money to buy drugs.

The middle-aged man has targeted a post office, an off-licence and a corner shop in the Lewes Road area of Brighton.

Each time he has opened his jacket to reveal a ten-inch carving knife to terrified shop assistants - but only ever demands £40 for a "fix."

The latest robbery took place on Saturday at Milner Wines, in Milner Road, and followed similar attacks on the Elm Grove post office on November 22 and two at Bradley's Convenience Store in Upper Lewes Road on November 25 and December 2.

Massimo Redaelli, who has owned Bradley's for two years, said: "The guy came up to the counter and pulled out this huge carving knife.

"He looked like he was in an altered state and I was scared for my life. When someone has a knife like that you don't argue, so I handed him the money.

"The following Saturday it happened again, almost identically. I couldn't believe it. I've seen this guy walking around the area since and he needs to be caught as soon as possible."

Bradley's narrowly avoided being hit for a third time by the robber on Saturday, just a few minutes before he went on to target Milner Wines.

Co-owner Nick Brown was on duty and spotted the man walking towards the shop. He said: "I saw him coming and jumped up and locked the door so he couldn't get in. He started banging on the door with his shoulder but soon realised it was locked and walked off.

"We have never had any trouble here until this, but now we have to be on our guard all the time."

Kaz Aslan, owner of Milner Wines, said: "I was in the shop on my own and the guy came in and asked for cigarettes. When I turned around he had a massive knife pointed at me. I nearly jumped out of my skin.

"He told me he needed the money to buy drugs but it was early and there wasn't much in the till so I gave him £10 out of my wallet and he ran away. I dread to think what would happen if someone tried to deny him the cash."

Police have launched an urgent appeal for information and have released CCTV images of the robber.

Det Con Angela Harvey, of Brighton CID, said three of the attacks had taken place on a Saturday when the robber might be unable to get his prescribed medication.

She said: "It seems that in desperation this man goes out to rob on Saturdays in order buy illegal drugs to feed his habit.

"He is a menace to society and appears to be stepping up his level of violence.

"If anyone from the local drug dependency units recognises him, we appeal for them to provide police with a name, even if they do so anonymously.

"He is clearly desperate and I would also urge him to come forward and seek help for his drug addiction to put an end to this before someone gets seriously injured."

The robber is described as in his 40s or early 50s, around 5ft 10in, with greasy lank black hair and some missing teeth.

Anyone with information is asked to call police on 0845 6070999 or Crimestoppers anonymously on 0800 555111.

To view the CCTV footage of the latest incident, click here