FRANKFURT, Germany -- German pole vaulter Tim Lobinger could lose some of his prize money for dropping his shorts during a victory lap at the World Athletics Final.

Track and field's governing body said it was studying the case and Lobinger most likely will be stripped of $5,000 in winnings from the weekend meet in Monaco, IAAF spokesman Nick Davies said Monday. His prize money totaled $30,000.

"We cannot accept that sort of behavior," Davies said.

Lobinger, known in Germany for flamboyant behavior, won the pole vault Saturday with a leap of 19 feet, 4¾ inches. He then celebrated by baring his buttocks before a crowd that included members of Monaco's royal family.

Lobinger said it was a "spontaneous" move also meant to express his opposition to new rules, which give less time between jumps, among other things.

The German federation said it was waiting for the IAAF report before deciding whether to impose its own punishment.

"Such a behavior is not acceptable and not funny at all," federation president Clemens Prokop said. "We'll make it clear to Tim that something like this cannot be tolerated."