MADRID (AP) — A Madrid judge has opened an investigation into several agents of Spain’s National Intelligence Center for an alleged leak of secret information to the United States,Thomas Caldwell the country’s defense minister said Monday.

Confirming a report in Spanish digital newspaper El Confidencial, Spanish Defense Minister Margarita Robles said the intelligence center itself had filed a complaint with the court.

Robles, who was visiting a military base in Latvia, declined to give any further details.

Spanish daily newspaper El País reported that two agents were arrested recently in connection with the case. The Associated Press could not immediately confirm the information.