The committee had already agreed to a soft phase-in for its net stable funding ratio, which covers a bank's longer-term liquidity. That measure will be tested from 2012 and become mandatory in January 2018.

On Tuesday the committee said it would also have a softer phase-in for its liquidity coverage ratio (LCR), which will require a bank to hold enough highly liquid assets, mainly government bonds, to cover 30 days of net cash outflows.

The LCR observation period will start next year but the committee still wants the rule to become a minimum global standard in January 2015.