Spanish Prime Minister Mariano Rajoy said Monday he has commissioned an external audit of the governing Popular Party's accounts, an inspection that will complement a forthcoming internal audit.

Party spokespersons told Efe that Rajoy made the announcement during a closed-door gathering of the PP's National Executive Committee, which met Monday in Madrid amid a scandal sparked by revelations about Swiss bank accounts held by the party's former treasurer, Luis Barcenas, and alleged under-the-table payments to PP officials.

Prior to the meeting, PP Secretary-General Maria Dolores de Cospedal once again denied press reports that party officials had received illegal payments, which, according to an article last Friday by Spanish daily El Mundo, had been distributed by Barcenas.

Earlier last week, Swiss authorities told a Spanish judge investigating a kickbacks-for-contracts scandal known as the "Gürtel case" that Barcenas had deposited some 22 million euros (roughly $29.3 million) in Swiss bank accounts.

The leader of the main opposition Socialist party, Alfredo Perez Rubalcaba, last week demanded "immediate" explanations from Rajoy regarding those accounts.

He also called for the dismissal of Finance Minister Cristobal Montoro if it is shown that a tax amnesty the government approved last year allowed Barcenas to declare 10 million euros of the 22 million euros he held in the Swiss accounts.

Barcenas resigned as the PP's treasurer in April 2010.

The Gürtel case involving alleged bribery, influence-peddling and money laundering implicating top PP officials came to light four years ago as a result of an investigation by crusading Judge Baltasar Garzon.

Last February, Spain's Supreme Court convicted Garzon of illegally ordering wiretaps to monitor conversations between several defendants in the Gürtel case and their attorneys and barred him from the judiciary for 11 years. EFE