Pupils should be taught other languages such as Mandarin in school, a report for the British Council says.
The report says Spanish, Mandarin and Arabic are languages of the future
The current dominance of the English language poses "serious" economic and political disadvantages for the UK, the study claims.
UK graduates who speak only English will lose out to multi-lingual workers from other countries, the council says.
The warning comes as pupils in England are no longer required to study a language beyond the age of 14.
From September 2004 the compulsion for all secondary school pupils to study a modern language up to GCSE or the equivalent level was removed.
But, in December last year, the government went some way to quell the concerns of critics.
Schools minister Jacqui Smith said, from September 2006, schools must ensure at least half of their pupils study a foreign language until they are 16.
Ethnic minority groups' input
Now the British Council, which promotes international education and cultural relations, is calling for urgent action to teach other languages.
"The UK's best defence against the threat of the spread of English is, in fact, to learn other languages," said author of the report - English Next - David Graddol.
"We have to think carefully about which languages those are," said Mr Graddol.
"French for example is declining as an international language, but Spanish, Mandarin and Arabic are all languages of the future.
"Ethnic minority groups in the UK may well prove to be a major asset in this effort."
Popularity of English
The report estimates that two billion people will soon be speaking or learning English - for example, nearly 60% of primary school children now learn English in China.
"In the new, rapidly emerging climate, native speakers may increasingly be identified as part of the problem rather than the source of a solution," the report said.
"They may be seen as bringing with them cultural baggage in which learners wanting to use English primarily as an international language are not interested.
"Native speaker accents may seem too remote from the people that learners expect to communicate with."