The High Court, Spain's highest criminal tribunal, has been investigating Luis Barcenas since Spanish media in January reported that he had for years used a slush fund to make undeclared payments to top party officials, including Prime Minister Mariano Rajoy.
The 55-year-old was already under investigation since 2009 over his alleged involvement in a kickbacks scheme with companies that organised events for the party known as the Gurtel case.
As part of his investigation into this affair, examining judge Pablo Ruz of the High Court wrote in a judicial writ published that Barcenas had €25,125,675 ($33,517,700) in an account in Swiss bank Lombard Odier in 2007.
The account was no longer "operational" after October 28, 2009, he added in the writ.
Ruz in February slapped a travel ban on Barcenas after questioning him about another Swiss bank account where the former treasurer had €22 million.
The High Court ruled in March that there was a link between the Gurtel affair and the alleged slush fund and assigned the investigation into the two cases to Ruz.