PALMA DE MALLORCA, Spain (REUTERS) - The Spanish king's son-in-law appeared before a judge on the island of Mallorca on Saturday to respond to charges of tax fraud in a six-million-euro embezzlement case that has eroded public support for the once-popular royal family.

The scandal and other corruption cases in which politicians are accused of taking millions of euros in bribes have enraged Spaniards at a time when unemployment has soared to 26 per cent in a deep recession.

Inaki Urdangarin, a former Olympics handball player who is married to the king's daughter, the Infanta Cristina, is accused of using his powerful connections to win public contracts to put on events on the Mediterranean island of Mallorca and elsewhere in Spain.

His Noos Foundation is suspected of overcharging for organising conferences about the business of sports and hiding the proceeds abroad.

In a statement before the judge's questioning, Urdangarin, 45, distanced the royal house from the foundation's business.

"The royal house had no opinion, didn't advise on, authorise or back any activities for which I was responsible at the Noos Foundation," he said, according to sources in the courtroom.

"On the contrary, when the accusations arose, the royal house recommended I ceased any activity not considered appropriate for my institutional status, which I did."

Dozens of police officials guarded the courthouse in Palma for the closed-door hearing where Urdangarin was being questioned by Examining Magistrate Jose Castro.

Near the courthouse, a few hundred protesters chanted and held up signs reading "Down with the monarchy" and "They call this a democracy but it isn't".

In Spain's legal system, lengthy pre-trial investigations are carried out by an examining magistrate, or judge. Urdangarin is charged with fraud, forgery, embezzlement and corruption. If convicted, he could face a prison sentence and fines.