Thieves have struck more than a dozen times in a spate of school burglaries.

There were four break-ins in Horsham in the last week and schools in East Grinstead and Crawley have also been hit.

The alarm was triggered at Tanbridge School, Guildford Road, Horsham, about 5.20am last Tuesday.

Later the same morning, police were called to Farlington School, Nowhurst Lane, Broadbridge Heath, after a window was forced open and electrical equipment stolen.

Four youths were seen running from the school at 6.30am on Tuesday morning and driving away in a yellow Peugeot 205, in the direction of the A29.

Last weekend, damage was discovered at Penthorpe School, Church Street, Rudgwick.

A door was forced and computer equipment stolen.

Rikkyo School in Horsham Road, Rudgwick, was also broken into overnight on Monday.

Maureen Johnson, the headteacher of Tanbridge House School, said: "This is our fourth break-in since January.

"They have been stealing our projectors that link to electronic white boards. They have taken 16 of the ones we bought at Christmas over the course of two break-ins.

"The other two break-ins have been for laptops. We have had about £6,000 worth of equipment taken in all, including a couple of laptops and a printer.

"At other schools they have taken plasma screens but we don't have any.

"The thing that dismayed me is that when we contacted the police we were told that there had been a lot of other break-ins already and we hadn't even been aware it was happening.

"You wouldn't expect something like this to happen at 5.20am. The children have been very disappointed as we only had the equipment for a week.

"The problem is we can't really lock up the equipment as it is in-situ.

"Schools are big targets and the implication of this is that schools are going to have to fund additional security.

"money spent on enhancing security is money that would otherwise have been spent on more equipment that we are going to need for improving learning.

"We are now reviewing all our security measures to find a way forward. By stealing this equipment they have deprived the children of valuable resources.

"On top of that they are doubly penalised because money that would have been spent on them will have to fund security."

Patrols have been stepped up and Detective Inspector Nick May urged the public to report anything suspicious near schools.

Alan Haffenden, a crime prevention officer for Sussex Police, said laptop computers, flat screen monitors and overhead screens were the main targets.

He said: "Most of the items will be marked with the school name or a West Sussex County Council security sticker.

"The sticker may have been removed and the items may have been offered for sale as old school equipment.

"Don't be fooled. These criminals are depriving our children of the technology they need for a good education in our high- tech society.

"It is vital that residents who live near schools are vigilant and report anything suspicious at the time."

Jane Robinson, communications manager at West Sussex County Council, said: "We obviously try our best to ensure that all security precautions are taken as far as the schools are concerned, for instance, with things like CCTV and alarms.

"But I am afraid that we can't make schools burglar proof as they have to remain nice places for children to learn."

Detective Sergeant Pierre Serra, leading the investigation, appealed for witnesses or anyone with information to call 0845 6070999.