Attempts by Greece to identify account holders in Switzerland ran into difficulty on Monday with the Greek finance ministry ruling out the use of stolen data and Swiss banks refusing to name lawmaker clients.

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The ministry told parliament that Greece would not use Swiss bank data saved on CDs purchased by some German authorities as the material could be deemed illicit "industrial espionage", the state-run Athens News Agency said.

Last week, it was revealed that the Swiss Bankers Association rebuffed a request by Greek parliament in early 2012 for the identification of Greek lawmakers with accounts in Switzerland.

The association had replied in July that it had no policy of forwarding such requests, and that lawmakers should contact Swiss banks directly.

Struggling to avoid bankruptcy since 2010, Greece has been trying to clamp down on perennial tax evasion, but with limited success.

The Bank of Greece was reported in July to have information on 403 Greeks who had moved at least €100,000 (121,000 francs, $131,000) abroad in 2010, whilst claiming to have zero income.

And the finance ministry in February said Greeks had legally moved €16 billion abroad in the last two years.

On Monday, the finance ministry said that instead of giving information to Greece, Bern was taxing account holders and transferring a portion to Greece.

As a result, the ministry said Athens gained over €5.9 million from 2010 tax receipts and some €9.9 million for 2009.