FRANKFURT (Reuters) - The euro zone's biggest banks would fare better in case of stress than two years ago as they have amassed capital and made headway in fixing their balance sheets, the European Central Bank said on Friday after a stress test of the bloc's 37 biggest banks.

The banks entered the test with an average Common Equity Tier 1 capital ratio of 13 percent, above the 11.2 percent two years ago, and would still hold a 9.1 percent capital ratio in case of an adverse scenario, above the 8.6 percent seen in 2014, the ECB said.

The ECB added that all but one bank showed CET1 capital levels well above the benchmark of 5.5 percent applied in 2014 in the hypothetical adverse scenario.

(Reporting by Balazs Koranyi; Editing by Catherine Evans)