Luis Barcenas: Spain Popular Party's ex-treasurer in jail
A judge has ordered that Luis Barcenas, the ex-treasurer of Spain's governing Popular Party (PP), be held without bail until his corruption trial starts.
The ruling came after Switzerland informed the court that Mr Barcenas had transferred money from Swiss accounts to banks in the US and Uruguay.
In light of the revelations, prosecutors argued that the politician was a flight risk.
Mr Barcenas and his wife deny charges of tax evasion.
The couple are suspected of falsifying documents on their tax statements between 2002 and 2006.
Mr Barcenas is also accused of keeping up to 48m euros (£41m) in secret Swiss bank accounts. Prosecutors allege that some of the funds stem from illegal party donations or kickbacks.
But the ex-treasurer has denied this, saying that all of the money was made through overseas investments, real estate and art dealings.
High Court Judge Pablo Ruz handed down his decision after Mr Barcenas and his wife had been called in to testify on Thursday.
Dozens of people heckled the couple outside the court, the Spanish newspaper El Pais reports.
In March, prosecutors discovered what they described as unusual transactions of more than 600,000 euros over a five-year period relating to bank accounts held by Mr Barcena's wife, Rosalia Iglesias.
She has admitted that she was neither working nor receiving a steady income during that period.
The case is part of a broader investigation into claims of alleged illegal financing of the PP. The party, which is led by Prime Minister Mariano Rajoy, has rejected the allegations.
Mr Barcenas resigned as party treasurer in 2009 after being implicated in the slush fund case, which has become known as the Gurtel scandal.