Access World, formerly Pacorini Metals, said on Jan. 21 it had become aware of fake warehouse receipts circulating in its name and urged holders to seek authentication.

Warehouse companies issue receipts for metal stored in their facilities as proof of ownership, which are often used as collateral for bank finance.

"We note that currently all relevant forged warehouse receipts we have seen have been in the name of Access World Logistics (Singapore) Pte Ltd... and have been solely across nickel," it said in a statement.

Access World also said that it would provide authentication for clients' certificates on Feb. 10-15, after which it would honour "duly authenticated original warehouse receipts".

Metals markets were rocked more than two years ago by a $3 billion fraud at Qingdao port in China, when a firm allegedly duplicated warehouse certificates to pledge metal as collateral for multiple bank loans.

(Reporting by Eric Onstad; editing by Jason Neely)