Greece's central bank said on Monday it activated a bank rescue fund to save Proton Bank, effectively nationalizing the small lender that is under investigation for possible violation of the country's money-laundering laws.

It is the first lender to be nationalized under the Financial Stability Fund (FSF), a safety net set up by Greece and its international lenders for banks that need to recapitalize but cannot raise funds in the market.

Analysts said the move had to do with Proton's own business problems and not with the country's severe debt crisis.

"After recommendation by the Bank of Greece, the Finance Ministry proceeded to apply to Proton Bank a new law about the restoration of banks," the Bank of Greece said in a statement.

The Bank of Greece said Proton was split into a "good bank" where all of its private sector, government deposits and sound assets were transferred. The good bank will have the FSF backstop as its sole shareholder and retain the trade name Proton.

"The 'good bank' is well capitalized, with a capital adequacy ratio that is well above the regulatory threshold. It has access to euro-system liquidity through the Bank of Greece," the central bank said.

According to the finance ministry, the new Proton Bank has a capital adequacy ratio of 10.6 per cent. The Bank of Greece has told the country's lenders they will have to maintain a Core Tier 1 ratio of 10 per cent from January 2012.

Proton, with a network of 31 branches and a current market value of about €11m, had total assets of €3.8bn at the end of the first quarter.