Confidential patient records could be lost unless "urgent action" is taken to stop doctors carrying them around on unsecure computer discs, a new survey suggests.

Almost nine out of 10 doctors asked carried the tiny discs, called "memory sticks", containing patients names and dates of birth as well as X-ray results, diagnoses and treatment, the vast majority without any password protection, the research shows.

The clinicians who carried out the research said there was "no reason why this lack of security would not be mirrored in surveys across every hospital in the UK".

They warn that unless the Government acts the NHS will join the string of organisations and government departments that have lost millions of supposedly safe records. The Department of Health said that carrying around unsecured records was a breach of data security laws, and that David Nicholson, the chief executive of the NHS, had written to all senior NHS managers to remind them of their responsibilities to protect patient records.

The study, of 105 doctors at a London teaching hospital, found that 90 per cent carried memory sticks.

Two thirds of the disks carried sensitive patient information but just five were protected by a password.

The study, given to the Health Service Journal (HSJ), warned that the sticks can be attached to keys or ID badges which could easily be misplaced.

One of the doctors who carried out the study, a surgical registrar, said that, in the past, patient information would have been kept in individual doctor's notebooks, which would have held much smaller amounts of information than the disks.

"Traditionally this would be in doctors' notebooks and loss of that would be a breach of data security but now the problem is that people have hundreds of thousands of kilobytes of patient information which gets put on these sticks and carried around," the registrar added.

A spokesman for the Department of Health said: "Any breach of patient security is unacceptable. We have urged the HSJ to provide details of their survey to the relevant trust so they can take appropriate action to protect patient confidentiality."

The survey will come as further embarrassment to the Government, which has been hit by a series of scandals over missing data.

Last month a computer memory stick containing information on thousands of criminals was lost.

In June confidential documents about al Qaida's operations in Pakistan and the security situation in Iraq were left on a train and later handed to the BBC, while that same month more secret government files were also found on a train.

Last year the Government admitted that computer discs containing the personal information of 25 million people who claimed child benefit had gone missing.

Mike Penning, the shadow health minister, said: "The Government's shocking record on data losses demonstrates for itself how vitally important it is that we maintain the security of the public's data, particularly when it is of such a sensitive clinical nature.

"Patients rightly expect their personal details to be protected. Unfortunately, this survey exposes the chaos inherent in Labour's approach to data security."