The US Department of Justice (DoJ) and the Commodity Futures Trading Commission are investigating at least 10 major banks for possible rigging of precious metals markets, the Wall Street Journal reported, citing people close to the inquiries.

DoJ prosecutors are scrutinising the price-setting process for gold, silver, platinum and palladium in London, while the CFTC has opened a civil investigation, the newspaper said.

The banks are HSBC Holdings, Bank of Nova Scotia, Barclays, Credit Suisse Group, Deutsche Bank, Goldman Sachs Group, JPMorgan Chase & Co., Société Générale, Standard Bank Group and UBS Group, the Journal said.

Standard Bank spokesman Erik Larsen declined to comment on the report. The other banks, the DoJ and CFTC did not immediately respond to requests for comment.

The CFTC issued a subpoena to HSBC Bank USA in January seeking documents related to the bank’s precious metals trading operations, HSBC said on Monday.

The DoJ also issued a request to HSBC Holdings in November seeking documents related to a criminal antitrust investigation it is conducting in relation to precious metals, HSBC said.

Precious metal benchmarks have come under increased regulatory scrutiny since a scandal broke in 2012 over manipulation of Libor interest rates.

The banks operating the precious metals benchmarks, known as the fixes, said last year they would no longer administer that process.