MAJOR telecoms operators have warned that it could be impossible to telephone some countries after the turn of the century because of the so-called "millennium bomb".

While large operators in the US and Britain are investing heavily to ensure their systems are free of the bomb - the inability of some computer systems to distinguish between this century and the next operators elsewhere are behind in their preparations.

British Telecommunications, which has set up a programme to ensure its systems would function correctly, has written to its counterparts abroad to ascertain their preparedness.

Mr Paul Harborne, head of the BT programme, said: "We believe some European operators are working on it but is anybody taking any action at all in the Far East?"

He is chiefly concerned that the world's operators should not only eliminate the bomb from their systems but have time to spare to test the way they work together.

AT&T, the largest US operator, for example, has established a project team under Mr George Brucia, a vice-president, and aims to have the work completed by January 1st, 1999.

The company said: "We see this more as a task to be carried through than a problem. But if it is not completed in time, it will be a serious problem."

The International Telecommunication Union, the Geneva-based organisation which co-ordinates the activities of national operators, will, for the first time, discuss what action to take in talks beginning on May 20th.

The bomb results from the common software practice of storing the year in a date as two digits - 97, rather than 1997 - to save memory.

After December 31st, 1999, affected computers may malfunction in unpredictable ways because of their inability to recognise a 21st century date.