The European Union is preparing a rewrite of international capital requirements as part of a growing effort to soften the blow of regulations on struggling banks.

The European Commission will announce a sweeping plan as early as next month for enacting global standards, including a requirement for lenders to have more stable funding to weather a future crisis. The EU's executive arm is debating ways of softening the rule's impact on trading in derivatives and short-term funding markets that could spare banks billions of dollars in costs.

"Our aim is legislation that supports financial stability, but allows banks to lend and support investment in the wider economy," Valdis Dombrovskis, the EU's financial services chief, said earlier this month. The bloc's rules need to be "as growth-friendly as possible," he said.