primaries should forget teaching other languages until pupils have got the hang of French, according to Rowland Constantine, chairman of the Independent Association of Prep Schools and head of New Beacon School, Sevenoaks in Kent.
He said that primaries should not forsake European languages to dabble in Mandarin and Arabic.
The Government has announced primaries will be free to choose which languages they study as part of a new drive to promote the subject in primary schools.
Primaries in Cambridgeshire, Derbyshire and Northamptonshire are already teaching Latin and Japanese as part of the Discovering Languages project.
But Mr Constantine said: "If you allow people to have a go at anything they'll end up with expertise in nothing. The best way is to start with French."
A survey of 500 prep schools found that 494 taught French, 146 taught Spanish and 93 taught German. Mandarin was offered in only 13 of them.