French teaching unions on Thursday called for a strike to protest "unacceptable working conditions" as a severe heatwave shatters temperature records in the country.

"The health of staff and pupils, as well as their working conditions, are being put at risk," the unions said in a joint statement, denouncing a "blatant lack of preparation".

With most of France under red alert, the heatwave is expected to reach its peak on Thursday, but many areas will remain very hot into the start of next week.

"The health of staff and pupils, as well as their working conditions, are being put at risk," the unions said in a joint statement.

Listen to the team at The Local discuss the soaring temperatures in schools in this week's Talking France podcast - download here