LONDON/MELBOURNE (Reuters) - Australia and New Zealand Banking Group ANZ.AX is seeking to uncover who was behind a metals fraud in Asia that cost it "substantial losses" and led to transfers of $151 million to the United States, according to court papers filed in California.

A man walks past a branch of the Australia and New Zealand Banking Group Ltd (ANZ) in Sydney October 29, 2013. REUTERS/David Gray/File Photo

ANZ, Australia's third-biggest lender, filed papers on June 6 asking the U.S. District Court in San Francisco to allow it to interview U.S. witnesses about a fraud that involved fake ownership documents for nickel stored in Asian warehouses owned by commodities group Glencore GLEN.L.

ANZ and Glencore declined to comment.

As part of a complex series of financial transactions, ANZ ended up with ownership documents for nickel stored in Singapore and South Korea, but discovered they were fraudulent when it tried to sell the metal, the court papers said.

ANZ has not yet filed a lawsuit, but the bank told the U.S. court it planned to do so in Asia once it discovered who was behind the fraud.

ANZ “has every intention of pursuing causes of action against... fraudsters, once their identities are known”, the papers said.

This is the second legal action that has emerged following the announcement in January by Glencore's metals warehouse firm Access World that it became aware of fake warehouse receipts circulating in its name. Earlier this month, a court filing in London's High Court showed French bank Natixis CNAT.PA had sued metals broker Marex Spectron for $32 million that Natixis said it lost due to fake warehouse receipts for metal stored at Access World depots.

Marex had said in a statement it rejected the claim and issued a separate claim against Access World for an unspecified amount because it said the warehouse operator had verified the receipts as being authentic.

Natixis and Access World had declined to comment.

NICKEL WORTH $306 MLN

The fraud was uncovered following repurchase transactions between ANZ and two Hong Kong firms involving 84 warehouse receipts for nickel of which 83 turned out to be fake, the court papers filed by ANZ said.

ANZ's court filing included copies of the purchase contracts, showing the transactions involved 32,964 tonnes of nickel, which at current benchmark prices CMNI3 would be worth about $306.4 million.

The deals were arranged by broker ED&F Man, which was not involved in the fraud and was cooperating to identify those responsible, ANZ added in the legal documents.

“ED&F is not involved in this legal action and has no further comment to make,” the broker said in an emailed statement.

ANZ said in the U.S. court papers that it had already unearthed information in Hong Kong after it asked courts there for access to bank records.

For example, those bank documents, included in the U.S. court filing, showed transfers of $151 million from the two Hong Kong firms involved in the nickel trades to people and entities in California.

ANZ told the U.S. court it wanted to interview those parties in California that received the funds.