Norway's Historical Museum officials said the soldier, who was not identified, was told to return the ancient coins and a small metal bottle to Afghanistan, as he may have violated laws against taking national treasures from their countries of origin, Aftenposten reported Friday.

"In Afghanistan, the laws can be different from Norway's, but such old items would almost certainly be covered by export restrictions," said Christopher Prescott, an archaeology professor at the University of Oslo.

Hakon Ingvaldsen, head of collections at the museum, said the coins were up to 2,000 years old.

"The museum can't take into possession things that belong to another country's cultural heritage," Ingvaldsen said.