The British subsidiary of French train and turbine maker Alstom paid around $8.5 million in bribes over a six-year period to win transport contracts in India, Poland and Tunisia, Britain's leading fraud prosecutor alleged on Tuesday.

Alstom Network UK, which was charged with six offenses of corruption and conspiracy to corrupt in July, allegedly paid bribes to win train infrastructure orders for the Delhi Metro and tram and infrastructure deals in Warsaw and Tunis between 2000 and 2006.

The case comes at a tricky time for the French parent, which has agreed to a $16.9 billion sale of most of its power business to U.S. conglomerate General Electric in a deal that gives the French government an option to become a shareholder.