One of Greece's biggest banks has filed a lawsuit against Reuters claiming 50 million euros in damages over a story that exposed a series of property deals between the bank and companies run by the family of its executive chairman.

Piraeus Bank in Athens has sued both the news agency, a unit of Thomson Reuters Corp (TRI.N), and the article's author, reporter Stephen Grey. The lawsuit accuses Reuters of malicious defamation and of wishing «to harm the entire Greek banking system."

The Reuters special report, headlined «A Greek banker's secret property deals» and published on Apr. 2, reported Piraeus had rented at least seven properties that were owned by a series of private investment companies directed among others by the wife and two children of the bank's executive chairman, Michalis Sallas, and financed by Piraeus bank loans.

The lawsuit says: «The bank never bought or leased any property, particularly illegal ones, from its chairman or his family."

The article was based on a study by Reuters of Greek corporate records and company statements, documents filed in Greek land registries and interviews with legal, accounting and property experts.

In a written statement, a Piraeus spokesman said: «Piraeus Bank has already started legal proceedings in the competent Greek Courts against Reuters as a result of its inaccurate and highly defamatory report.» The spokesman said the bank possessed «sufficient evidence and data» to disprove allegations in the article, but the bank declined to provide details.

Reuters director of global communications Barb Burg said: «We continue to stand by our story. Due to the ongoing legal process, we cannot comment further at this time."

Prior to publication, Piraeus and Sallas declined to answer questions about the deals, which had not been declared to shareholders.

The bank, whose stock price has fallen 97 percent since its peak in 2007, is due to receive up to five billion euros as part of a bailout backed by European taxpayers.

The lawsuit says that the article's publication caused the bank's shares to tumble 14.5 percent, representing a loss to the bank at the time of 46 million euros. The shares had more than recovered their value a week later before declining again.