The UK's four major banks have passed EU stress tests, although five Spanish banks failed, the Committee of European Banking Supervisors (CEBS) said.
RBS, Lloyds, HSBC and Barclays all passed the healthchecks, which assessed whether banks would be prepared for future economic downturns.
But Spanish banks Diada, Espiga, Bianca Civica, Unnim and Cajasur all failed, as did German bank Hypo Real Estate and Greece's ATEBank.
The banks that did not pass the test will now be required to hold more capital.
Banks were assessed on three different scenarios; a benchmark stress, a more adverse macro-economic stress and a country-wide stress.
UK banks are already required to meet the FSA's interim capital regime introduced in November 2008. This requires them to be able to meet a severe stress over a forward-looking period exceeding 4% Core Tier 1 capital at all times.
On Wall Street, US stocks lost some ground following the results. The Dow Jones, which had earlier gained 40 points, dropped marginally into the red, falling 0.12% to 10,309.
Markets are comparing the EU tests to the one conducted by the US in May 2009, when 10 large banks needed to raise $65bn (£43bn) of fresh funds.
Experts at Credit Suisse point out the European banking sector has already been bolstered by €200bn since then.
Two global vehicles
'Further plug advice gap'
Must appoint separate CEOs and boards
Advisers do come out well
Will report to Mark Till