More than £20,000 of high-tech equipment has been stolen from Keighley schools in the past three months.

Thieves have targeted computer-linked overhead projectors in 22 attacks on 12 different schools. They have returned to some schools to rip more of the projectors from classroom ceilings.

Holycroft Primary School, off Oakworth Road, last week became the latest school to be hit by the burglars.

Students responded by designing their own posters highlighting the theft and writing letters criticising the thieves.

The machines, which cost up to £1,000 each, enabled teachers to project images from PCs on to whiteboards.

Keighley detective Paul Harrison said this week that the raids were being carried out by specialists. He said: "There's obviously an outlet in the Keighley area because so many are going. They're state-of-the-art projectors that hang from the ceiling."

Det Insp Harrison said schools had to realise they played an important role in crime prevention.

He suggested schools should close curtains in rooms containing projectors, hide remote controls, security-mark the machines and if possible lock them in a safe out of school hours.

Anyone with information about the burglars, or where the projectors are being sold, should phone the police on 01535 617085 or 617059.