Such borrowing has been rising as banks resort to cheap ECB loans to help mitigate the impact from the health crisis.

Euro zone banks borrowed a record 1.31 trillion euros from the ECB in mid-June, taking advantage of negative interest rates to meet growing demand for credit from companies hit by the deepest recession in living memory.

Launched six years ago, the ECB's targeted-longer term refinancing operations (TLTROs) were redesigned earlier this year to help the economy cope with the coronavirus crisis and banks will get the cash for a rate as low as minus 1%.

The negative interest rate means banks that tapped the auction will earn 0.50% for one year with no strings attached and 1% if they simply refrain from shrinking their loan book.

In August 2012, Spanish banks had taken an all-time high of 411 billion euros from the ECB, when the country's financial turmoil reached a peak and weak lenders were granted a 41.3 billion euro aid package from the European Union that summer.

(Reporting by Jesús Aguado; editing by Andrei Khalip)