Spanish prosecutors are investigating a possible diversion of public funds by a foundation once headed by Iñaki Urdangarin, who is married to Princess Cristina, the youngest child of King Juan Carlos and Queen Sofia.

The chief anti-corruption prosecutor for the Balearic Islands, Pedro Horrach, questioned several people Thursday in connection with the probe of the non-profit Instituto Noos.

Horrach has no immediate plans to ask supervising magistrate Jose Castro to subpoena Urdangarin - the Duke of Palma - for questioning as a potential defendant, sources close to the investigation told Efe.

On Wednesday, the prosecutor took a statement from Diego Torres, a Noos director during Urdangarin's tenure as president and the duke's successor as head of the foundation.

Horrach and his team suspect Urdangarin and Torres established a web of shell corporations to facilitate the diversion of public money going to Instituto Noos.

Investigators are also looking into the 2.3 million euros ($3.1 million) the Balearic regional government paid Instituto Noos in 2005 and 2006 to organize conferences on sports and tourism.

The royal household issued a statement expressing "absolute respect" for the actions of the judiciary.

Iñaki Urdangarin wed Princess Cristina in October 1997. The couple and their four children now live in Washington, where the duke is an executive with Spanish telecom giant Telefonica.