Offices are becoming increasingly unhygienic as more workers eat lunch at their desk, making them more prone to illness, according to new research.

A hygiene firm said tests showed computer mice were the filthiest part of workers' desks, containing more than three times the levels of bacteria-related contamination than on the average toilet seat.

Computer keyboards were the second most unhygienic piece of office equipment, said Initial Washroom Hygiene, which carried out tests on over 150 separate items in 40 different workstations in a number of offices.

Male workers were found to have dirtier workstations.

Peter Barratt, technical manager at Initial Hygiene, said: "It is now common for office workers to spend their lunch hour eating at their desk, often surfing the web or continuing to type at the same time.

"This leaves crumbs and other food residue all over the work station, but particularly on mice and keyboards, making them ideal places for bacteria and other micro-organisms to survive and multiply.

"In addition, because they are electrical devices, these items aren't cleaned as regularly or as thoroughly as other parts of the office, or even as the desks themselves."

Loading Slideshow

• How To Prevent Catching Illnesses

• Wash Your Hands

  Wash your hands frequently and thoroughly with soap and water, particularly after using the toilet and before preparing food.

• Don't Share Flannels Or Towels

  Avoid sharing flannels and towels with anyone who has had or has the superbug, or anyone who may be exposed to it in any way.

• Disinfect Surfaces

  Disinfect any surfaces or objects that could be contaminated with the virus. Wash the items separately and on a hot wash to ensure that the virus is killed.

• Keep Your Toilet Clean

  Keep the toilet and surrounding area clean and disinfected to avoid any cross-contamination.

• Avoid Raw, Unwashed Food

  Avoid eating raw, unwashed produce and only eat oyster from a reliable source. <a href="http://www.huffingtonpost.com/mobileweb/1969/12/31/three-quarters-british-oysters-norovirus-winter-vomiting-bug_n_1118617.html" target="_hplink">Note that oysters are known to carry the virus.</a>