EU court mortgage ruling could make Spanish banks repay 4 bln eur - Bank of Spain source

MADRID, Dec 21 (Reuters) - The European Court of Justice's ruling overturning a Spanish court sentence that had capped banks' liabilities for mortgage floor contracts could force Spanish banks to repay customers slightly more than 4 billion euros ($4.16 billion), a Bank of Spain source said on Wednesday.

Banks will now have to compensate customers for what they lost on the mortgages, which could not fall below a benchmark, before May 2013, when Spain's Supreme Court declared them invalid if they had not been presented clearly.

The ruling, which banks and analysts were not expecting, is final and cannot be appealed.

(Reporting By Jesús Aguado; Editing by Angus Berwick)