THEY cause more damage than the flames, cost way too much and other tactics work much better, say Dorset school governors after revealing none of their schools targeted by arsonists now have sprinkler systems installed.

Their revelation follows the national launch in Bourne-mouth yesterday of a campaign by teaching union ATL calling for the government to make it a legal requirement for sprinklers to be installed in all new-build and school and college refurbishments.

According to the Arson Prevention Bureau, 20 schools a week suffer firebug attacks, and a third of these occur during school hours.

Some 90,000 children every year find their education seriously hampered as a result.

But the cost of installing a sprinkler system in a new school ranges from 1.5 per cent to 2 per cent of the total building costs.

Lytchett Minster School suffered millions of pounds of damage when arsonists hit in 2000, causing so much destruction that pupils have been left coping in 32 mobile classrooms. The destroyed parts of the school have still not been replaced, although the £12m plans are well advanced.

Chair of governors, Ray Griffin, said: "There's a comprehensive fire strategy in place for the new build - although this doesn't include sprinklers.

"Here, the main building is Grade II listed so unless a sprinkler system can be adapted, it would cause more damage than it would hope to save.

"As part of our new build we will have fire blankets and doors, the smoke will vent above head height and the building is designed to evacuate 600 students in 2.5 minutes.

"The roof will also have heat sensors and sections can be blown off to release smoke."

At Ashdown Technology College in Poole, firebugs des-troyed the music hall in 1997.

"Even with the fire brigade, who were on scene very quickly, they could do nothing to save it because there was no sprinkler system," said former chair of governors Richard Harrison.

"There was a lot of damage to the music room and main hall, and smoke damage to the whole school.

"It took 15 months for the rebuild because we also took the opportunity to add two classrooms.

"But the rebuild did not include a sprinkler system.

"Ashdown is on the government's list to be rebuilt as part of a national scheme in about three years time, so I hope a sprinkler system will be incorporated."

QE School in Wimborne is about to rebuilt because its facilities need modernising - not due to arson. But the county council project manager said: "We carry out fire risk assessments on all schools according to DfES guidelines and one has been done for QE.

"We've decided that sprinklers aren't needed. Sprinklers don't provide a means of escape and are just there for building protection.

"We are still in the process of drawing up a comprehensive strategy for QE and will probably be taking a similar approach to that of Lytchett Minster."