Santander, the euro zone's biggest lender, on Thursday said its core capital under Basel III rules would reach 12 percent at the end of the year.

The bank, which posted a 25.9 percent drop in net profit from a year ago to 1.205 billion euros ($1.6 billion), also said it had already returned 31 billion euros of cheap European Central Bank loans, out of an estimated 35 billion euros it took.

(Reporting by Sarah White, editing by Julien Toyer)