Spain's high court has admitted a new complaint by Banco Popular Español SA shareholders, who are requesting that the bank's resolution and subsequent sale to Banco Santander SA be canceled, according to ABC.

It said the complaint — the first step in legal proceedings to open up a potential case — had been filed July 25 by shareholders representing 2% of the bank's capital.

Popular was acquired by Santander on June 7 after European authorities deemed the bank "failing or likely to fail" as Popular succumbed under the weight of its €36.8 billion nonperforming assets. The sale has been the object of various legal actions, with shareholder and consumer groups filing complaints to the European Court of Justice.

In a separate report, news agency Europa Press said the court had thrown out a complaint by a group of former Popular customers, requesting the immediate cancellation of the bank's sale.