Hospital staff have been banned from using a computer screensaver helping scientists find a cure for cancer.

Managers at Oxfordshire's major hospitals claim downloading the research program from the Internet is "dangerous" because of the risk of computer viruses.

The screensaver's designer, Prof Graham Richards of Oxford University, has called the move "deplorable".

The Oxford Radcliffe Hospitals NHS Trust said the software contravened security and patient confidentiality policies, meaning employees at the John Radcliffe, Radcliffe Infirmary and Churchill hospitals in Oxford and the Horton in Banbury -- including 287 cancer staff -- cannot use it.

The screensaver was designed to quicken the search for a cancer cure. PC users can download the program which, when their computers are left idle, shows 3-D images of molecules sent via the Internet from a central database.

It checks molecular structures to see if they could be beneficial in the fight against cancer, before sending the findings to the university. The process would take one computer decades to achieve.

ORH managers have prevented hospital PCs from logging on to the appropriate website and told staff that the screensaver, which uses 20 per cent of a computer's power, would increase the traffic on its network, which is needed for vital hospital work.

Prof Richards said study sponsors Intel had made sure there were no virus risks and that no technical problems had been reported by any of the 1.2m PCs in 209 countries that are currently using the screensaver.

He added: "As for the increase in traffic, the whole point of the screensaver is that it only works when the computer is not being used. I'm sure hospital PCs already have screensavers and if they don't they will damage their monitors."

Andrew Stevens, ORH director of planning and information, said: "While the objectives of this project are very worthwhile and important, we have strict security criteria which prevent us from using our computers in this way."