The level of doubtful loans -- mostly real estate credits -- reached 11.38 percent of total loans, up from 11.23 percent in October, the Bank of Spain said in a report.

It was the highest level since existing records began in 1962.

The total value of doubtful loans was 191.63 billion euros ($258 billion) in November, the central bank said.

Spain secured agreement in June last year for a European Union rescue loan of up to 100 billion euros to shore up its banks, which have been struggling with bad loans since a 2008 property crash.

A frist instalment of 39.5 billion euros was disbursed in December, of which 37 billion euros went to four banks, including hardest-hit Bankia, that have been rescued with state money and nationalised.