An Italian judge has ordered four foreign banks to stand trial for aggravated fraud stemming from a 2005 derivatives swap for a 1.68 billion euro ($2.32bn) bond issued by Milan, legal sources said.

UBS, Deutsche Bank, Germany’s Depfa and JPMorgan Chase & Co have been ordered to stand trial in a test case for billions of euros in derivatives taken on by Italian cities nationwide.

The judge also ordered 13 bank officials and former Milan city employees to stand trial on the same charges, the legal sources said.

JPMorgan and UBS had no immediate comment. Deutsche Bank and Depfa were not immediately available to comment.

Milan, Italy’s financial and fashion capital, says it faces a 100 million euro loss on the deal, the biggest bond issue by an Italian city.

Milan is also suing the banks in the civil courts for 239 million euros in total liabilities.

Milan is the most prominent Italian city among hundreds that raced to sign up for derivatives contracts in an attempt to cut interest costs on their debts.

Almost 500 small and large Italian cities are facing mark-to-market losses of 2.5 billion euros on the contracts, according to the Bank of Italy. Analysts say that figure will balloon when interest rates go up.

Italy’s central bank put the notional value of derivatives contracts at 24.1 billion euros in June 2009.

In the southern region of Puglia, prosecutors also are seeking to bar Merrill Lynch, a unit of Bank of America Corp, from government contracts for two years. The move stems from derivatives losses from 870 million euros in regional bonds.