The bid would potentially place the bank in direct competition with other funds including U.S. investors Blackstone and Centerbridge which are considering a 3-billion-euro offer, two sources said last week.

The sprawling complex located in Boadilla del Monte outside of Madrid was sold to Marme Inversiones and leased back for around 50 million euros a year by the lender.

Santander declined to comment on the sale.

(Reporting by Jesus Aguado; Editing by Paul Day)