Up to 60bn euros ($78bn) will be needed to bail out Spain's banks, says the country's second biggest lender, BBVA.

The results of independent stress tests of the Spanish banking sector will be published on September 28. But previews are already being sent to the country's financial institutions.

According to BBC, the Spanish government has already put in place economic reform plans that would allow it to apply for a bailout immediately.

Spain's conservative Prime Minister Mariano Rajoy has in the past insisted Madrid would not become the fourth European capital in recent years to apply for such a bailout, but sources indicate such a program is now likely.

Spain's banking sector needs recapitalizing, and much of the money would come from 100bn euros in European Union funds already pledged by eurozone finance ministers in June.

"We'll get a figure of around 70, 75 or 80 billion euros," BBVA's Chairman Francisco Gonzalez said.

That figure includes around 20bn euros already allocated to troubled banks, which means 50-60bn euros is still required.