Without teachers and parents to regulate new modes of communication, children are replacing time-consuming, properly constructed language with a quick-fire mix of letters, numbers and punctuation.

Research by advertising agency McCann-Erickson claims that this will have a lasting affect on written language as children continue the shorthand into adulthood. The agency interviewed some 100 five to 100-year-olds to identify future trends in communications technology.

Robin Lauffer, the agency’s executive planning directors, said: “We are witnessing a communications revolution which children have adapted to very quickly. Our language is changing in front of our eyes.”

Mobile-phone users in the UK are sending more than half a billion text messages a month, according to the Mobile Data Association. There are 1 million mobile owners under 15, and nine and 10 year olds are the fastest growing market.

Brevity is essential in text messages: “for you”, for instance, would be displayed as “4U”. Punctuation symbols, such as smiling faces: ”:-)” or sad ones: ”:-(” which mean happygood or sadbad, are used instead of words.

The trend comes amid growing worries about children’s competence in writing. Last year, only 54 per cent of 11-year-olds reached the expectedlevel in writing compared with 78 per cent in reading.

A raft of measures, including the first Government-approved grammar book in decades and training in language skills for teachers look likely to make this school year the unofficial “year of writing”.

Nigel de Gruchy, general secretary of the National Association of Schoolmasters Union of Women Teachers, said modern communications threatened to damage the integrity of the English language.

“Disgusted from Tunbridge Wells should be more concerned about the lapses of the Internet and e-mails than lapses in the teaching of English. Dropping grammar and replacing sentences with jargon will damage the language.”

Dr Bernard Lamb, of the Queen’s English Society, claimed acronyms and abbreviations were a degenerate form of English, could be deciphered wrongly and were potentially inefficient in the long run.

But Anne Barnes, former president of the National Association for the Teaching of English, said abbreviations that pre-dated e-mail had become acceptable. She said: “The use of the expression OK, which is now part of normal speech, horrified some people.” She added that pupils could learn to employ informal and formal language as required. “Everybody has a bilingual ability, using different language for different purposes.”

“Modern communications mean children are communicating more frequently and more freely, which is tremendous.”