French Environment Minister Jean-Louis Borloo has signed a decree to end electricity giant EDF's quasi-monopoly over the running of the country's hydroelectric dams, a source said Wednesday.

The decree ends the preferential treatment accorded to Electricite de France in getting tenders. EDF currently runs about 80 percent of the 399 hydroelectric projects opened to bidding.

EDF turned into a public company in 2004 and a law came into force two years later ending the preferential treatment. But only a few small dams were opened to competition.

The source said tenders would be launched soon for dams whose current contracts expire in a few years. The new contracts will start from 2012.

In a parliamentary report made public in early July, deputy Christian Kert called for strict guidelines in the floating of new tenders.

"We have to be absolutely sure of the expertise of those who eventually take over dams run by EDF," he said, adding that the "security" of the dams was of paramount importance.

Hydroelectricity accounts for 12 percent of the total power produced in France.