Spanish prison authorities say that the brother-in-law of Spain's King Felipe VI has begun serving a nearly six-year sentence for fraud and tax evasion.

An official with the Interior Ministry's prison management division said Inaki Urdangarin arrived Monday morning at a prison near Avila, about 100 kilometers north of Madrid. The official spoke anonymously, in line with internal rules.

Urdangarin, a 50-year-old former Olympic handball medal winner married to the king's sister, Princess Cristina, is the closest person to the ruling Bourbon family to be imprisoned.

He was convicted to five years and 10 months in prison for embezzling about 6 million euros ($7 million) by exploiting his position in the royal family to obtain public contracts.

Cristina was fined 136,950 euros ($158,600) as a beneficiary of the scheme.