U.S. regulators are scrutinizing whether prices are being manipulated in the world's largest gold market, according to the Wall Street Journal.

The Commodity Futures Trading Commission is scrutinizing whether prices are being manipulated in London, the world's largest gold market. The CFTC is looking at issues including whether the setting of prices for gold—and the smaller silver market—is transparent. No formal investigation has been opened.

The system of setting gold prices in London is unusual and involves a twice-daily teleconference involving five banks – Barclays, Deutsche Bank, HSBC, Bank of Nova Scotia and Société Générale – while silver is set by the latter three. The price fixings are then used to determine prices worldwide.

The news of the potential investigation comes after analysis of a similarly unusual system - the process used to determine the London interbank offered rate, known as Libor – uncovered manipulation and triggered multi-billion dollar fines against a group of banks.

The CFTC began investigating complaints of misconduct in the silver market in 2008 after some investors argued that a steep price decline that summer was the result of market manipulation.

The CFTC never announced results of that investigation or officially confirmed it had closed.