Editorials in the British Medical Journal (BMJ) and the Lancet say the present system can be abused by research teams to hide disappointing results.

They call for a central compulsory worldwide register of all controlled clinical trials - which would be open for public inspection.

This would allow people to find out exactly what is under investigation in any particular disease area.

And it would stop different research teams wasting time and money by launching identical and expensive trials.

A register would also force doctors to register exactly which organisation, such as a drug company, is paying for the study.

In a joint editorial, the editors of The Lancet and the BMJ say the present system is "chaotic", and call on the editors of all medical journals worldwide to promote such a scheme.

The NHS, which contributes to the funding of the majority of UK clinical trials, already operates a searchable database of research on the Internet - and others have attempted to launch registers.

At present, the organisation of clinical trials in the UK is not governed by any statutory controls.

However, research papers from flawed trials, such as instances where there is a conflict of interest affecting the researcher, can be rejected by journals such as the Lancet and the BMJ.

Doctors can be struck off

In the UK, the top journals contribute to the Committee on Publication Ethics, which tries to uncover badly-run or unethical trials.

If it finds doctors have falsified trial results, it can refer the matter to the doctors' disciplinary body the General Medical Council.

In the worst cases, a doctor could be accused of serious professional misconduct, and if found guilty, they can be struck off from practice.

The potential problems affecting medical research were illustrated this week by an investigation launched by the New England Journal of Medicine, one of the world's most highly-rated.

It is looking into whether the author of a positive review of two hair-loss treatments failed to disclose her own financial ties to the drug makers.

Dr Vera Price said that treatment of hair-loss had been advanced by Propecia and Rogaine.

But the Journal is investigating whether she fully disclosed funding she received from the makers of the two drugs.