A non-governmental organisation, the Berne Declaration, has published a detailed report on the impact of plans to build a major dam in south-eastern Turkey, and urged the Swiss government to rethink its participation.
It accused the government of complicity to breach international law for awarding export risk guarantees to companies engaged in the project.
The Swiss foreign ministry has rejected these accusations out of hand, but welcomed the expert report as a good document.
The report, released by the Berne Declaration on Sunday, is based on research done by Professor Astrid Epiney of the University of Fribourg. The organisation says the Ilisu dam project goes against international agreements on the appropriate use of shared natural resources.
It says it would also breach accords seeking to prevent actions which have a significant cross-border impact on the environment.
The Berne Declaration argues in the report that if the Swiss government were to confirm the award of SFr470 million francs worth of export risk guarantees, it would be aiding the Turkish government to break international law.
The Swiss government agreed in principle in November 1998 to award the guarantees, but must still make a final decision.
Under the Turkish plan, an international consortium led by Switzerland's Sulzer Hydro is to build Turkey's largest dam on the Tigris river, about 60 kilometres from the Iraqi and Syrian borders.
The project involved relocating about 20,000 people in the predominantly Kurdish region.
A foreign ministry expert on international law, Roberto Balzaretti, rejected the claims against the government. He told the "SonntagsZeitung" newspaper that the concept of complicity to break international accords did not even exist in international law.
swissinfo with agencies
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