Spanish Princess Cristina is to face trial for tax fraud in what is to be Spain's first attempt at prosecuting a royal.

A judge ruled Monday that Princes Cristina de Borbon, the sister of current King Felipe VI, and her husband Inaki Urdangarin are to stand trial on a series of tax fraud and embezzlement charges related to a nonprofit ran by the husband, the BBC News reported.

Prosecutors from Spain's Balearic Islands say Urdangarin and a former business partner used his sports nonprofit Noos Institute to embezzle $7.5 million dollars of public money. Some of that money was allegedly channeled into other businesses, including a consulting firm called Aizoon, which Urdangarin co-owned with Princess Cristina, according to the Associated Press.

The 49-year-old princess is accused of tax fraud relating to about $3.2 million of the over $7 million her husband is accused of misusing, the BBC reported. The alleged wrongdoing was discovered after a four-year investigation that began in 2010.

Both Cristina, who is sixth in line for the throne, and her husband have denied the charges against them. Lawyers for the princess said she expressed surprise over the indictment. Under Spanish law, a defendant can escape prosecution if the victim- in this case the Spanish state- does not support the charges, The New York Times reported. The state did not support the charges.

Miquel Roca, Princess Cristina's lawyer, said he plans on appealing the decision made by the High Court of the Balearic Islands. The princess faces up to four years in prison if convicted.

"It's a serious, surprising and exceptional situation," Roca said, The NY Times reported.

The case comes during a time of increasing distrust for Spain's royal family, which was restored to power in 1975. The previous king, Juan Carlos, abdicated the throne to his son earlier this year after he was criticized for taking a lavish hunting trip while the country was in the midst of a financial crisis.

Princess Cristina's trial is expected to begin sometime next year.