Europe's top drug regulator weighed into the medicine pricing debate on Wednesday, arguing a smarter and faster pharmaceutical approval system was needed to help rein in the spiraling cost of new treatments.

In exchange for speeding up the approval process, society would expect manufacturers to charge less for innovative medicines, European Medicines Agency (EMA) Executive Director Guido Rasi said.

Companies are under fire over pricing on both sides of the Atlantic, with Europe's state-backed health systems struggling to afford costly new therapies, while U.S. presidential candidate Hillary Clinton has pledged action on the issue.

Although the job of the EMA - Europe's equivalent of the U.S. Food and Drug Administration - is simply to ensure drugs are safe, effective and of good quality, Rasi believes the watchdog can also make an important contribution on the cost side.

"As regulator, we want to recommend innovative medicines for approval that are affordable. That is why we are fostering a better model for the development of medicines," he told reporters in a briefing.

Central to this is the EMA's so-called "adaptive pathways" initiative, under which drugs would be approved early for restricted patient populations based on small initial clinical trials.

Approval would then be expanded progressively, based on additional studies, reflecting the reality that evidence develops continually as clinical data builds up. As with the existing regulatory system, a medicine could be pulled from the market if new data revealed unexpected problems.

Rasi said this approach would be "leaner and more efficient" and, importantly, should help bring down the cost of developing new drugs.

"Our expectation is that companies will reflect this by reducing the price of medicines for the benefit of patients and for the sustainability of our healthcare systems," he said.

The new adaptive licensing system could reduce "by years" the time taken to win approval for a new medicine and should be applicable in future to many, although not all, new medicines, Rasi added.

Advances in medical science mean the world has seen a bumper haul of expensive new medicines approved for use in the past two years. Treatments for cancer, in particular, often cost around $10,000 a month in the United States, although they are typically cheaper in Europe.

A rapid pace of drug launches is expected to continue in the years ahead, with 225 new drugs forecast to be approved between 2016 and 2020, according to a report from industry data firm IMS Health last month.

(Editing by Elaine Hardcastle)