MADRID (AFP) - Spain's Princess Cristina has been summoned to testify as a suspect in a corruption case, a court official said on Wednesday, a historic blow to the prestige of the royal family including her father King Juan Carlos.

It is the first time that a member of the Spanish royal family has been called to appear in a court of law on suspicion of wrongdoing.

The 47-year-old princess must testify as a suspect at the court in Palma on the Mediterranean island of Mallorca on April 27, the court official said on condition of anonymity.

"The royal household does not comment in any way on judicial decisions," a spokesman for the royal family told AFP.

The case, opened at the end of 2011, centres on allegations of embezzlement and influence peddling against her husband Inaki Urdangarin and his former business partner, Diego Torres.

The pair are suspected of syphoning off money paid by regional governments to stage sports and tourism events to the non-profit Noos Institute, which Urdangarin chaired from 2004 to 2006.