Teachers are having to decipher the abbreviated and occasionally obscure language of text messages when they mark their students' assignments.

Nearly two thirds of teenagers say they are incorporating the more informal style of texts when they submit written work at school, and half have abandoned basic principles such as capitalisation on occasion.

Short-cuts such as LOL - which stands for 'laugh out loud' - have been used by 38 per cent of students in their work, and a quarter have used emoticons - the little yellow icons which show a face smiling, or being angry.

An overwhelming majority, however - 73 per cent - say that using informal expressions such as these make no difference to their normal writing, and 15 per cent say that electronic communication has in fact improved their prose.

The study of 700 American teenagers by the Pew Internet and American Life Project gives an intriguing insight into the writing habits of young people, 93 per cent of whom say that writing "for their own pleasure" is important.

About seven in ten say that when they are writing 'for themselves', they prefer to do so by hand.

Cecile De Cat, a lecturer in the School of Modern Languages and Cultures at the University of Leeds, said the fact that 'text speak' was permeating other types of writing would not have a detrimental effect.

"What's at stake here is just the ability to express oneself in more than one register," she said. "As long as children are taught to use the standard spelling and to appreciate the difference between registers, this could even be positive."

A spokeswoman for the Association of Teachers and Lecturers, the education union, said that no teachers had complained of an inability to interpret their students' assignments.

Despite embracing the computers and the internet generally, 49 per cent of teenagers acknowledge that using word-processing programs to write would likely make them 'take short cuts', and 42 per cent said such programs would encourage poor spelling and grammar, the report suggested.

Two in five also said the likes of Microsoft Word would lead them to write too quickly and too carelessly.

James Billington, the US Librarian of Congress, said recently that the use of electronic communications by young people may be damaging "the basic unit of human thought - the sentence."

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