Goldman Sachs, BASF and two other major platinum and palladium dealers have been sued in the US in what lawyers for the plaintiff, Florida-based jewelry and police badges manufacturer Modern Settings, said is the first nationwide class action suit over alleged price-fixing of precious metals platinum and palladium.

In a complaint filed in the US District Court in Manhattan, seeking unspecified damages for alleged violations of US antitrust and commodities laws, Modern Settings accuses units of Goldman, BASF, HSBC Holdings and South Africa's Standard Bank Group of having conspired since 2007 to rig the twice-daily platinum and palladium "fixings" and the prices of futures and options based on those fixings.

Claiming that metals purchasers lost millions of dollars, the company charges that the dealers illegally shared customer data, used that information to engage in "front-running" of expected price moves and manufactured phantom "spoof" orders.

Platinum and palladium are used in catalytic converters to curb vehicle emissions in addition to dentistry and jewellery.

On Dec. 1, the London Metal Exchange will take charge of platinum and palladium price fixing and use a new electronic platform, which will replace a benchmark system established in 1989 and run by Goldman, BASF, HSBC and Standard.

Reports say regulators around the world have tightened scrutiny of pricing benchmarks in recent years after uncovering evidence of rigging in currencies and the London Interbank.

BASF, the world's largest chemicals producer, told US media it could not comment because it had not been notified of a complaint. The German group generated €2.36 billion in precious metals trading revenue in 2013. The London-based trading business is part of BASF's Catalysts division, which is the world's largest maker of catalytic converters.