Britain's reliance on its mother tongue is leaving UK businesses at a disadvantage, a committee of MPs has warned.
The House of Lords European Union Committee said British businesses will be "severely hampered" because language skills in the UK are falling behind those in other countries.
The decision by the Government to make languages optional at GCSE level in England will only serve to make the problem worse, it added.
Government policy is that, by 2010, every child aged seven to 11 should be able to learn a language.
Last month, ministers announced that they would spend another £115m on providing foreign language teaching in English schools.
But educationalists are worried. The exams watchdog the Qualifications and Curriculum Authority has warned recently that A-level French and German are in "terminal decline".
The peers, who were examining European Union plans to develop Europe-wide education schemes, said: "We conclude that the United Kingdom is already falling badly behind in language-learning capability.
"This will seriously limit British ability to take part fully in and benefit from the new EU programmes."
They added: "We are deeply disturbed by the evidence we have been given about the declining capacity for language-learning in this country.
Moves to improve primary school language teaching did get the thumbs up, but with the proviso that it would take many years to have any lasting effect.