Five hundred schoolchildren were kept indoors at break times today, while mystery foam was washed off their playgrounds.

Five hundred schoolchildren were kept indoors at break times today, while mystery foam was washed off their playgrounds.

Vandals used the foam to spray graffiti and a swear word over the playgrounds at Cromer's junior and infant schools - while at the nearby high school 25 skylight windows in three classrooms were also smashed.

Junior school head Steve Godson said staff discovered the foam on the ground and benches this morning, but when they tried to clean it up the asphalt began to come away, so they called the emergency services.

A similar attack had been carried out at the next door Suffield Park infants and nursery school, meaning a total of 500 pupils were not allowed outside during breaks until the problem was resolved.

Firemen used high pressure hoses to wash off the foam, and a hazardous substance officer called in to check out what it was, said fire service spokesman Martin Barsby. It appeared to be a cleaning agent, which turned out to be “not acidic, not alkaline and not dangerous”.

Mr Godson said the attack followed a similar graffiti incident around Christmas when offensive words were spray-painted on the front of the school building. The latest incident meant part of the playground would need resurfacing, and he was sad that the actions of those responsible were leading to such costs.

High school head Ron Munson said the smashed windows meant re-jigging some first lessons of the day, but there was no damage to the classrooms themselves.

Police confirmed that all three incidents had happened at the weekend, but that no-one appeared to have broken into the high school. Anyone with information about the vandalism on any of the sites should contact Cromer police on 0845 456 4567 or Crimestoppers anonymously on 0800 555 111.