Spottorno insisted on presumption of innocence and urged investigators to conclude their probe soon as he announced Urdangarin will for now be removed from the royal family's agenda and no longer attend any official ceremonies involving it.
Spottorno said it was not yet known if the princess would also stay away from such activities.
The couple and their four children now live in Washington, D.C., where Urdangarin works for Spanish telecommunications company Telefonica, S.A.
No court papers have been made public, but Spanish newspapers quote investigators as saying Urdangarin is suspected of having taking part of about euro6 million ($8 million) the foundation received from the regional governments in Valencia and the Balearic Islands for organizing events such as sports seminars.
The money is said to have gone to for-profit companies Urdangarin ran.
The case is part of a broader, long-running corruption probe involving the regional government in the Balearic Islands, the capital of which is Palma on the island of Mallorca.