The rush for silver coins has pushed the global market into an unprecedented supply squeeze, forcing some mints to ration sales and step up overtime while sending U.S. buyers racing abroad to fulfill a sudden surge in demand.

The Perth Mint has said that most of the demand last month came from the United States and Europe although buying from Asia, particularly Hong Kong, was also good.

The mint sold more than 3.53 million ounces of silver coins in September, it said in an emailed statement on Thursday, or about five times higher than the mint's August sales.