Banks in Europe should temporarily raise their capital reserves to help withstand market turmoil over the continent's debt, the president of the European Commission said as he presented a broad new crisis plan.
Jose-Manuel Barroso also said key European banks should not be allowed to pay out dividends or bonuses until they have raised their capital buffers to the new standards.
The fear gripping the financial sector now is that banks could take big losses on bonds they own from governments with shaky finances, like Greece.
That uncertainty is stifling lending - both between banks and to the wider economy - which threatens to throw the 17-nation eurozone into a new recession.
Mr Barroso did not give a specific figure for the new capital buffers but the full proposals, published on his website after his speech, suggested his proposal could require an accelerated implementation of new international rules on bank capital, the so-called Basel III rules.
Those rules increased the amount of low-risk assets that banks had to hold to back up their lending and investments, in order to decrease the chances that banks could fail in turbulent times.
A spokesman for Mr Barroso said it will be up to the national banking supervisors, together with the European Banking Authority, to define when the higher capital ratios have to be attained, how long they have to remain elevated and set the precise ratio.
To assess banks' capital needs, their exposure to all sovereign debt should be taken into account "in a transparent way", Mr Barroso said.
The Commission also asked for a "prudent valuation of all sovereign debt, whether in the banking book or the trading book" of banks. The international body that sets accounting standards recently complained that many banks were not taking adequate writedowns on bonds that they plan to hold until they mature.
Mr Barroso said if banks can't raise the capital on the market, they should get help from governments, who in turn can ask for money from the eurozone bailout fund.