A man found about 800 apparently genuine World Cup tickets in a plastic bag at a Frankfurt tram stop Thursday.

The city's transport authority said the finder brought the bag to its lost property office. They were then handed over to the German soccer federation.

"They seem to be genuine tickets," said Jens Grittner, a spokesman for the World Cup organizing committee, although he added that was not yet certain.

Organizers were trying to determine where the tickets came from and which matches they were for.

The monthlong tournament opens on Friday, when host Germany plays Costa Rica in Munich