Argentina men's soccer coach Javier Mascherano said the team's Olympic training base was robbed before its chaotic tournament-opening loss to Morocco on Wednesday.
The Argentina delegation filed a police complaint in Lyon, the prosecutor's office of nearby Saint-Etienne said Thursday.
"They went into training and they robbed us, in the Olympic Games," Mascherano said after his team's shocking 2-1 loss. "We didn't want to say anything after training, I don't think it helps anything. But obviously it's a bit disagreeable that these kinds of things happen."
Mascherano said midfielder Thiago Almada's watch was among the items taken.
It has been a troubled start to the Olympics for Argentina, which took gold in 2004 and 2008.
It's game in Saint-Etienne was suspended for nearly two hours after Morocco fans rushed the field and threw bottles to protest what appeared to be an equalizing goal from Cristian Medina in the 16th minute of added time.
The game was eventually resumed after fans were told to leave Stade Geoffroy-Guichard. The goal was overturned after being reviewed by the video assistant referee (VAR).
Morocco held on as they played out the final three minutes.
Argentina's soccer federation said it had issued a formal protest Wednesday to world governing body FIFA and would do "what is necessary" to guarantee the safety of players.