EXTRA police patrols are being deployed around a community where a robber has preyed on four pensioners inside a week.

Detectives think the man is becoming more aggressive and desperate and fear he will strike again in the Knuzden area of Blackburn.

They have received recent reports of someone matching the man's description in the community and have moved to prevent further incidents.

Det Insp Neil Hunter said: "These are the most despicable offences when people prey on the elderly.

"If the patrols result in gathering evidence then that's great, but also increasing the amount of patrols causes disruption which prevents other people becoming victims."

A 76 year-old woman, of Brantwood Avenue, became the latest victim on Tuesday when a man knocked on her door and asked for a drink of water.

Once inside, he grabbed the woman's arm and pushed her in the face as he demanded money. The woman managed to struggle free and push the man outside her home. She then locked the door and he fled empty-handed.

A man with a similar description terrified an 84 year-old woman in a brutal robbery at her home in Hozier Street on Saturday. He entered through an unlocked front door and stole money from the living room before confronting the woman.

Threats of violence were issued as he forced her to take him around the house in the search for more cash before he fled. She was left with severe cuts and bruising.

Last Wednesday two other incidents happened in Didsbury Street. A man called at the home of a woman in her 70s and pretended to be a council gardener.

He appeared to work for several minutes before asking for a drink of water. While she was in the kitchen, he stole a purse containing £60.

A few hours later a 70 year-old woman walking into her home was asked by a man if he could use her toilet. He stole credit cards and cash while she was in another room.

Each of the attacks are linked as the area, method, descriptions and times are similar. The man was white, aged 25, around 5ft 8in, with short, dark, hair. He was wearing a white vest, and has also been seen with a gold chain and blue jeans.

DI Hunter said: "The offender has become more desperate and aggressive as he has progressed. We are appalled by these offences and will do our utmost to prevent further ones."

Anyone with information should call Blackburn police on 01254 701777 or Crimestoppers on 0800 555 111.