The 500-page report reveals that none of the criteria it was asked to assess have been satisfied.
The report lists concerns over effects on people displaced by the dam, on archeological heritage, the maintenance of an adequate water supply to Iraq and Syria .
Balfour Beatty said it was still studying the report, but added that it was taking an active and responsible role in evaluating, with other parties, the environmental and social impact of the project in order to reach the right judgments.
Trade and Industry Secretary Patricia Hewitt is expected to make a decision on whether to grant £200m in export credit guarantees for the scheme in September.