* EMA says more transparency will increase R&D efficiency
* Says drugmakers will benefit from plan to release data
* EU agency being sued by two drugmakers over data release
LONDON, Oct 21 (Reuters) - Europe's medicines regulator has come out fighting for greater transparency for clinical trials, arguing that its controversial policy to end data secrecy will be "a boon to drug developers".
The strong defence of greater openness by the boss of the European Medicines Agency (EMA) and colleagues comes as the agency battles a lawsuit from two U.S. drugmakers over its plans to release data on their medicines.
The London-based watchdog has been on a collision course with much of the drugs industry since deciding to lift the lid on previously secret trial data submitted by companies as part of the application process for new medicines.
Researchers and patient groups want access to this raw data to improve third-party scrutiny and stress-test claims about drugs. But many companies fear that this will damage their businesses and undermine the ability to defend patents.
EMA Executive Director Guido Rasi, who has championed data transparency since taking over at the agency two years ago, and his colleagues say that industry concerns are misplaced.
Rather than reducing the incentive to invest in drug research, releasing data from clinical trials would help drug company scientists hunting for new medicines, they said in a paper published in the New England Journal of Medicine on Monday.
The paper, entitled "Access to patient-level trial data - a boon to drug developers", says that the sharing of detailed trial results would increase efficiency in drug development and improve cost-effectiveness by reducing duplication of effort.
"Contrary to industry fears, we argue that access to full - though appropriately de-identified - data sets from clinical trials will benefit the research-based biopharmaceutical industry," they wrote.
"It is ironic that the organisations that most resist wider access to data are the ones that stand to benefit so much from greater transparency."
A central concern among companies is that releasing raw data showing the effects of medicines on individual patients - whose identity is to remain hidden - would lead to "free riding" by rivals, who could avoid the cost of doing their own research.
It is an objection at the heart of the legal challenge to the EMA's policy by drugmakers AbbVie and InterMune , which in April won an interim ruling preventing the agency from releasing documents, pending a final court decision.
The EMA has since applied to have the injunction lifted and its appeal was heard in Luxembourg this month, but an EMA spokesman said it is unclear when the court will deliver its ruling.
In the meantime, demands for more transparency are growing, particularly in Europe, where Germany's Institute for Quality and Efficiency in Health Care recently complained that the EMA measures do not go far enough.
The debate has also crossed the Atlantic. The U.S. Food and Drug Administration is considering new ways to increases data disclosure, while the U.S. Institute of Medicine will discuss sharing of clinical trial data at a two-day meeting in Washington this week.