Warwickshire Police is appealing to parents and carers to warn children not to try to gain access to the former North Leamington School Site in Cloister Way.
The site, which was due to be converted into a state-of-the-art new premises for Castel Froma care home before these plans were shelved, has several warning notices but the police have had several reports about children entering the site recently.
A statement from the force says: “To clarify, the area is not safe, and children should not make attempts to access it. There is broken glass on the site which could cause injuries.
“The police are working together with the owners of the site and the council, to make it more secure.
“We are thinking of children’s safety.”
The school’s other former building in Park Road has already made way for a new housing estate while the former Manor Hall building was replaced by the new school site in Sandy Lane.
North Leamington School’s new building in Sandy Lane was opened in 2009 merging both the main school and its Sixth Form centre.