A former treasurer of Spain's ruling party appeared before a judge on Monday to explain how he amassed 22 million euros ($29 million) in a Swiss bank account, an amount he reportedly concealed from Spanish tax authorities.
Judge Pablo Ruz of the National Audience, Spain's top criminal court, will question Luis Barcenas over the origin of the money which according to Spanish press reports was held in the same of a Panamanian foundation, judicial sources said.
Prosecutors suspect Barcenas, who resigned as treasurer of the conservative Popular Party in 2009, of bribery, tax fraud and money laundering.
Barcenas arrived at the Madrid court in a black car but refused to answer questions from the dozens of journalists who were waiting for him.
Swiss officials informed a Spanish judge investigating a kickbacks-for-contracts scandal implicating top Popular Party officials known as the "Gurtel case" of the existence of the money in the bank account.
The Popular Party has denied any link to the money.
Barcenas has said that his fortune comes from sales of paintings and real estate, which contradicts a police report, according to local media.
He is at the heart of another scandal involving the Popular Party over allegations of under-the-table payments to senior party members including Prime Minister Mariano Rajoy.
Rajoy, Barcenas and the party have denied the allegations, which are based on account ledgers purportedly written by Barcenas and published in leading daily newspaper El Pais.
The newspaper published ledgers it says were kept by Barcenas, apparently showing payments including 25,200 euros a year to Rajoy between 1997 and 2008.
The main opposition Socialist Party has demanded that Spanish authorities seize Barcenas' passport to prevent him from fleeing Spain.