The U.S Justice department is investigating 10 U.S. based banks over alleged manipulation of the gold and silver price.

The Justice Department’s antitrust unit is now shifting its attention to the precious metals market after previously focusing on manipulation of financial benchmarks. A number of the world’s leading financial institutions are facing criminal charges over alleged manipulation of currency and interbank lending markets.

HSBC Bank confirmed on Monday that the U.S. commodities regulator and the Justice Department have demanded documents from bank regarding its precious metals dealings. The other banks under investigation are Standard Bank Group Inc, Bank of Nova Scotia, Societe Generale SA, Goldman Sachs Group Inc, Group AG and Credit Suisse Group AG.

In November JPMorgan, Bank of America and Citigroup settled currency manipulation accusations with the U.S. regulators. As part of the settlement the banks where required to review all their trading activities which could involve similar manipulation.

Deutsche Bank, Barclays and HSBC have all been sued in U.S. courts over accusations they manipulate the precious metals markets.