In recent years there have been a series of protests against a boom in dam construction in the region, which includes countries hoping to win EU membership.

In a report by several environmentalist groups, led by Bankwatch, campaigners said Serbia, Bosnia and Kosovo must change their renewables incentives schemes as soon as possible.

In 2018 about 70% of renewable energy incentives awarded in the region benefited small hydropower projects, the environmentalists said, despite serious environmental damage and limited potential to contribute to the energy supply.

The report said at least 380 small plants bellow 10 megawatts have been built since 2009, driven mainly by the availability of public financial support in the form of feed-in tariffs, but their contribution to power generation was just 3.6%.

Authorities and investors view hydro power as a green alternative to other sources of energy and say it could help the countries hit the renewable energy targets they need to meet to join the EU.

Under plans currently being considered by governments, a network of nearly 3,000 hydro plants could be built across the area, with about a third of them in protected areas.

Non-governmental groups Riverwatch and EuroNatur last year published a document showing that three-quarters of the rivers in the Balkans are so ecologically valuable they should be completely off-limits for hydro power development.

Bowing to pressure, some countries have started taking action. Montenegro is phasing out incentives and Albania approved a law in 2017 introducing an auction-based system for larger plants by 2020.

North Macedonia has also taken steps towards an auction system but left feed-in tariffs for hydropower intact, giving it an advantage over solar and wind.

"Only technologies which are still developing and whose costs are expected to fall further need support through state aid, especially solar and wind in cases where they would not be viable without incentives," the campaigners said in their report.

"Failure to tackle the integrity issues of the current renewables incentives schemes will slow down an already lagging energy transition in the region and cost it dearly," they added.

(Reporting by Maja Zuvela; Editing by Elaine Hardcastle)

By Maja Zuvela