FRANKFURT (Reuters) - Major clients will have to pay to deposit large amounts of cash at Commerzbank AG (>> Commerzbank AG) in response to negative rates charged by the European Central Bank, the bank said on Thursday.

The ECB move has turned the profitable business of taking deposits into a potentially loss-making activity, forcing banks to review their charges.

"The reason for this is the ECB's negative deposit rates. We will be careful in charging deposit fees and take special consideration of our clients' liquidity levels," the bank said, confirming a story first reported by the Wall Street Journal.

Clients needing short-term deposits will be encouraged to consider alternative investments than cash, said Commerzbank, Germany's second-largest bank.

Deutsche Bank (>> Deutsche Bank AG), Germany's biggest bank, also offered big clients investment alternatives to cash deposits such as time deposits, the bank said in a statement. A spokesman declined to comment further.

Euro zone banks have faced the risk that customers' cash deposits could turn into a burden since September, when the ECB began to charge banks 0.20 percent interest to park funds at the central bank.

The subject has been hotly debated by banks for at least a year, when Juergen Fitschen, co-Chief Executive of Deutsche Bank and head of the country's commercial banking lobby BdB, said banks would need to consider responses to the threat of negative rates by passing some of the costs onto clients.

Earlier this week, Fitschen said banks would need to decide on an individual basis whether and how to impose charges.

In order to boost inflation -- currently 0.4 percent -- and weak growth, the ECB has introduced a ream of policy measures such as negative interest rates, bank loans and an asset purchase programme.

(Reporting by Andreas Kroener and Thomas Atkins; Editing by Crispian Balmer)

Stocks treated in this article : Deutsche Bank AG, Commerzbank AG