The U.S. Justice Department is investigating whether the world’s biggest banks manipulated prices of precious metals such as silver and gold as it pushes to wrap up probes into currency-rate rigging, according to people with knowledge of the matter.

At least 10 banks, including Barclays Plc, JPMorgan Chase & Co. and Deutsche Bank AG, are being probed by the Justice Department’s antitrust division, said one of the people, who asked not to be identified because the matter is confidential.

Precious metals have come under scrutiny as authorities around the world investigate allegations that other financial benchmarks have been rigged. While the Justice Department’s probe is in its early stages, the Swiss regulator included the issue in a November settlement with UBS Group AG over currency-rate manipulation. British and German regulators have looked into the gold price-setting process and found no evidence it was rigged.

The U.K. Financial Conduct Authority is continuing to scrutinize firms’ behavior in relation to precious metals as part of continuing supervisory work spurred by the foreign-exchange probe. While the FCA doesn’t have authority over physical markets, it does regulate derivatives. In that context, it’s already issued one fine, ordering Barclays to pay 290 million pounds ($447.5 million) in May for a former trader who artificially suppressed the price of gold in 2012 using fake positions to avoid triggering a payout to a client.

HSBC Disclosures

HSBC Holdings Plc disclosed Monday that the Justice Department and U.S. commodities regulators have sought documents from the bank on precious-metals dealings. The London-based bank said it is cooperating in the probes.

Spokesmen for the Justice Department and the Commodity Futures Trading Commission declined to comment. Chris Hamilton, an FCA spokesman, declined to comment on its reviews.

The CFTC looked into the silver market already after receiving complaints and closed the probe in 2013, saying there was no basis for it to take action.

While the CFTC and FCA have already reached currency-rigging settlements with some banks, the Justice Department’s probes are still under way. These foreign-exchange manipulation probes are further along than the precious-metals case, and Attorney General Eric Holder said after the initial round of currency deals announced in November that its investigations should conclude “relatively soon.”

The banks under investigation also include Credit Suisse Group AG, UBS, Goldman Sachs Group Inc., Societe Generale SA, Bank of Nova Scotia, and Standard Bank Group Ltd., the person said. The Wall Street Journal reported late Monday that those banks were being investigated. The banks either declined to comment or didn’t immediately respond to requests for comment.

‘Conduct Issues’

The Office of the Comptroller of the Currency was also part of the November currency-rigging settlements. The three banks that reached deals with the OCC then — JPMorgan, Citigroup Inc. and Bank of America Corp. — were required to review and identify “other trading activities that could raise similar market conduct issues.” Those reviews triggered scrutiny of precious metals trading, another person said.

Benchmark-rigging probes have prompted procedural changes as well as fines. Control of the London interbank offered rate, used to calculate interest rates, was moved from the British Bankers’ Association to IntercontinentalExchange Group Inc. in the wake of that rigging scandal. The Financial Stability Board has advocated extending the trading window used to calculate foreign-exchange rates to five minutes from one minute, and charging fees for trades done at those rates, a step some banks have already implemented.

FCA Visits

For precious metals, the daily silver fixing, a price-setting ritual dating back a century, was overhauled last year with the help of the London Bullion Market Association after Deutsche Bank stopped taking part in the procedure. A similar telephone-based process for platinum and palladium was also replaced by an electronic, auction-based system as regulatory scrutiny increased over how market benchmarks are set, and the same will happen to gold fixings next month.

It wasn’t immediately clear which areas of precious metals the Justice Department is investigating.

The FCA also looked into metals benchmarks, and visited member banks involved in the gold fixing last year as part of its review, a person with knowledge of the review said at the time. It found “no clear evidence” the London gold fixing had been manipulated, an FCA official told a parliamentary committee in July.

U.S. Lawsuits

The German financial regulator also found no signs of rigging in the gold market, Raimund Roeseler, head of banking supervision at Bafin, said in an interview with Handelsblatt in January.

HSBC, Goldman Sachs, Barclays and Deutsche Bank are among banks that have been sued by investors and jewelers in the U.S. over claims they conspired to manipulate precious metals prices for years.

HSBC also is under a five-year deferred prosecution agreement with the Justice Department from a previous money-laundering settlement. The agreement requires the bank to cooperate in other probes.