Only one in three schools in England make all pupils study a foreign language at GCSE level, a survey says.
Languages should be compulsory say campaigners
Language experts complain that curriculum changes have led to languages being squeezed out.
Since September, schools in England have no longer been required to teach foreign languages to children over 14.
The National Centre for Languages, which commissioned the survey and report, is calling for an urgent rethink of policy.
The study showed a gap between state and independent schools, with 97% of independent schools keeping languages compulsory at GCSE.
Among maintained schools surveyed for the report, only 30% made children study a foreign language after the age of 14.
A year ago, that figure was 57%, the National Centre for Languages said.
The survey was based on 800 state schools and about 180 independent schools.
The government said the report ignored the positive effect of England's 200 specialist language schools, because they were not included in the survey.
Director of the National Centre for Languages, Isabella Moore, said the falling numbers of children taking languages to GCSE level would "leave school leavers short of vital skills and affect the competitiveness of British business".
"With 70% of businesses now involved in some form of international activity, the idea that languages are just for 'academic' pupils is short-sighted and
damaging to the economy," she said.
"There is an urgent need to re-think language provision in the 14-19 sector."
The government's policy is to encourage primary schools to teach languages.
A spokesman for the Department for Education and Skills said more
opportunities for younger children meant they would want to carry on studying
languages in later life.
"Already almost half of primary schools are offering language learning
compared to a fifth in 2001," he said.
"This will lead to increasing numbers of children learning languages
throughout their school careers and beyond.
"Secondary schools are still required to offer languages to those who want to
study them, and it is disappointing that this report ignores the impact of over
200 schools which now specialise in language teaching and the 14,000 more pupils
achieving a GCSE at grades A*-C compared to 1997."
The survey suggested regional variations in language teaching after the age of 14.
The lowest figures were in the north of England, where 23% of schools made children study languages after 14.
In the English midlands, the figure was 29%, while in southern England, including London, the figure was 36%.