LONDON (Reuters) - The British subsidiary of French train and turbine maker Alstom (>> ALSTOM) paid around $8.5 million (£5.27 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 offences 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 a $16.9 billion sale of most of its power business to U.S. conglomerate General Electric (>> General Electric Company) in a deal that gives the French government an option to become a shareholder.

Britain's Serious Fraud Office (SFO), which has been investigating Alstom for five years as part of an international criminal inquiry into alleged corruption, said in legal filings published after the first London court hearing on Tuesday that the Alstom unit disguised corrupt payments as consultancy agreements.

These agreements were struck by Alstom Network UK, certain directors and others with Indo European Ventures Pte Ltd and Global King Technology Ltd in India, Sagax Engineering Limited and Kavan BV in Poland and Construction et Gestion NEVCO in Tunisia, the SFO alleged in the document.

Parent Alstom stressed that the charges related to past misconduct.

"The company has been in communication with the SFO and seeks no more than a fair and appropriate resolution of the allegations made," a spokeswoman said.

If convicted, Alstom Network UK faces fines or a ban from competing for public contracts in the European Union. Its next court hearing at the higher Southwark Crown Court is scheduled for Oct. 6.

The British investigation was spawned by information from the Swiss Attorney General, which ordered Alstom to pay 38.5 million Swiss francs (£25.63 million) for corporate negligence in 2011 because it had failed to stop bribery.

Three executives of Alstom's U.S. unit in Connecticut have since pleaded guilty and admitted paying bribes on behalf of the company. Four years ago, the SFO arrested three UK board members over allegations of bribery, money laundering and false accounting.

Siemens (>> Siemens AG), Alstom's German rival, paid about $1.6 billion in 2008 to settle U.S. and German allegations it used bribes for years to win contracts.

(Additional reporting by Natalie Huet in Paris; Editing by Pravin Char)

By Kirstin Ridley

Stocks treated in this article : ALSTOM, General Electric Company, Siemens AG