Germany's Postbank, a unit of Deutsche Bank, is to scrap free current accounts for millions of customers in an effort to offset the burden of the European Central Bank's negative interest rates.

"The market environment, especially low interest rates, make it ever harder to earn money from current accounts," Postbank board member Susanne Kloess said in a statement.

From 1 November customers will be charged €3.90 a month unless they have monthly inflows of €3,000 or more, in which case they will still have cost-free access to a premium giro account, Postbank said.

The announcement comes as Bank of Ireland is reportedly set to be the first domestic Irish bank to charge customers who deposit large amounts of money with the lender, also as a result of the impact of the ECB's negative interest rates for depositors. 

The move underscores the pressure German banks are facing to find fresh sources of revenue since the ECB's money-printing policy slashed the margin between short-term borrowing and long-term lending.

Banks previously used that margin to subsidise other products, such as free giro accounts for customers.

A small cooperative bank in the Bavarian Alps last week also caused a stir by saying it planned to charge wealthy clients a fee for holding large deposits.

 "The gratis culture is changing; we've seen some moves already and there will be more," Michael Kemmer, the head of Germany's BDB banking association, said this week.

A Postbank spokesman declined to specify how many customers would be required to pay for their accounts, but said it would be the "vast majority" of Postbank's 5.3m giro account holders.