It concluded many children avoid them altogether because they are unhygienic and threatening places.

The whole ambience must be comfortable and this was not the case in the majority of these toilets Sue Vernon, University of Newcastle

Researchers from Newcastle and Gothenburg universities are calling for urgent legislation passed to set higher standards.

Sue Vernon, of the University of Newcastle upon Tyne, said: "Going to the toilet is more than just a physical reflex.

"The whole ambience must be comfortable and this was not the case in the majority of these toilets."

Mrs Vernon and her colleagues made their own observations and also did a comparative study of nearly 400 children in England and 157 in Sweden who rated their school toilets.

Common complaints were unflushable toilets and not enough hand basins.

Both British and Swedish youngsters said they feared being "baptised" by bullies who often pushed pupils' heads into the toilet bowl and flushed it.

Mrs Vernon said: "Discussions with other European colleagues suggest that school toilets are also a problem for many other European children."

Current legislation in Britain and Sweden is limited to the number of toilets per pupil but Mrs Vernon said the results of the study, published in The Journal of Childcare, Health and Development, show this is not enough.

"This needs to be extended to include acceptable standards of hygiene such as availability of soap, towels, washing facilities, toilet paper and adequate privacy," she added.