The chairman of the European Banking Authority (EBA), Andrea Enria, warned at a conference in Berlin on Thursday that even banks who passed the European Central Bank's (ECB) stress tests should not feel too secure, Reuters reported.

"The story is not over, even for the banks who passed it," said Enria.

The European Central Bank said on Sunday that 25 banks failed due to a capital shortfall and 13 banks have to raise an additional €10 billion in capital. Most banks have already taken steps to solve their problems.