Wartime helmets and gas masks should be banned from classrooms because they pose a health and safety risk to pupils and teachers, a watchdog has warned.
The historical items are inappropriate for youngsters and school staff to handle or wear as they may contain traces of asbestos, according to updated advice drawn up by the Health and Safety Executive (HSE).
Schools often use these types of relics in history lessons to teach pupils about the conflicts, and the new information comes as events begin taking place around the country to mark the start of the First World War a century ago.
The HSE's document warns that schools which have items of war memorabilia that are suspected to contain asbestos should stop using them, double bag them in plastic and tape them shut. Arrangements should be made to have the items destroyed, unless they can be made safe by a licensed contractor or contained in a secure display case.
It says that replica gas masks and helmets that do not contain asbestos are available for schools to use as teaching aids.
The updated advice has been published after the HSE conducted an analysis of a number of vintage gas masks and held discussions with the Imperial War Museum about how they store artefacts containing asbestos.
This work confirmed that "no gas masks should be worn or handled by children or teachers," the HSE said.
The HSE's analysis found that the majority of vintage masks contained asbestos, often the more dangerous "crocidolite" or "blue" type of the substance, adding it is very difficult to decide whether or not a mask contains asbestos simply by looking at it, and that some will be in very poor condition.
The advice goes on to say that the Imperial War Museum had reviewed its collections for its First World War Galleries and discovered that the majority of the British Army "Brodie" helmets that were issued during the Great War contain "chrysotile" or "white" asbestos in the helmet liner.
"Accordingly, the advice in relation to these items is the same as for gas masks," the document says, "it is not appropriate for children or teachers to wear or handle any artefacts that potentially contain asbestos."
Paula Kitching of the Historical Association said such items should be made safe were possible.
"Now this information has been found it has got to be taken seriously," she told The Times.
"But it would be a shame if schools were to dispose of such things. If they can be made safe, that is the course of action they should take. These are historical artefacts."