POLICE are increasingly concerned about the number of incidents involving the use of knives after a third off-licence raid in just four days.

In the past week, three shops in Hartlepool, Teesside, have been targeted by thieves armed with weapons.

There have been a number of other knife-related incidents in the Cleveland area, including the fatal stabbing of a refugee in Middlesbrough town centre.

There was a knife amnesty in the Cleveland Police area in 1996, but officers have so far stopped short of calling for a similar initiative.

A police spokeswoman said: "We are certainly monitoring the situation and, if it is deemed necessary, an amnesty will be considered."

Although the off-licence attacks took place within a mile of each other, police are keeping an open mind as to whether they are linked.

In the latest incident, a knife-wielding masked raider threatened shop assistants before making off with a small amount of cash from Gillen's shop, in Brierton Lane, Rift House.

A spokesman for Hartlepool police said: "It is very unusual to get three similar incidents in four days in such a localised area. We are investigating and looking at CCTV tapes from the shop."

In the first raid on Monday, at 7.30pm, a masked raider threatened a shop assistant with a knife at the Booze Buster shop, in Fens Shopping Centre, before making off with £200.

The following night, at 5.30pm, two shop assistants were threatened by a masked man with a knife at Booze Buster, in Wynyard Road, Owton Manor, before the raider made off with a money box.

Anyone with any information about the raids should contact Hartlepool police on (01642) 302129