Glencore Plc-owned metals warehouse company Access World urged its receipt holders to seek authentication for receipts it did not directly issue, warning that fake receipts are circulating in its name, Reuters reported Jan. 30, citing a statement from the warehouse firm.

Warehouse receipts for commodities like copper and aluminum can be used as collateral for bank financing, and fake warehouse certificates have been used for fraud, such as the case of China's US$3 billion Qingdao port scandal in 2014, which stemmed from a company that allegedly used duplicate certificates as collateral for multiple bank loans.

According to the newswire, Glencore declined to comment on the matter.