Computer keyboards can harbour more harmful bacteria than a lavatory seat, it has been claimed.

Many users are at risk of becoming ill with stomach bugs, according to the comsumer group, Which?

It warned that "qwerty tummy", named after the first six letters on a keyboard, could sweep through workplaces after tests on equipment in its own London offices showed alarming result.

One keyboard was so dirty that a microbiologist ordered it to be removed, quarantined and cleaned.

It had 150 times the acceptable limit for bacteria and was five times as filthy as a typical lavatory seat.

Anyone who eats a sandwich or piece of fruit, having been tappin on such a keyboard, can pick up bacteria that could lead to a stomach upset. The scientist swabbed 33 keyboards for food poisoning bugs e.coli,coliforms,staphylococcus aureus and enterobacteria and compared the result to those found on a lavatory door handle.

Four of the keyboards were considered a potential health hazard and one was "condemned".

Two had " warning levels" of staphylococcus aureus and two others had "worryingly elevated" levels of coliforms and enterbacteria, "putting users at high rish of becoming ill from contact".

Found that one in 10 people never clean their keyboard, while 20 per cent never clean their mouse. Around half cleaned their keyboard less than once a month. The modern practice of "hotdesking". in which staff sit at different desks every week, means that workers do not know has been using their keyboards before them.

Kidner said workers and home PC users should give their keyboards a regular clean, adding : "It's quite sim[le to do and could prevent your computer becoming a health hazard."

Says users should uplug computers before wiping surfaces with a damp, soft, lintfree cloth. Keyboards should be unplugge, turned upside down and shaken.