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Goldman Sachs and HSBC are among four platinum and palladium dealers to be sued in New York for allegedly fixing the price of the metals.

The four companies are said to have rigged prices for eight years. BASF and Standard bank were also sued in the first lawsuit of its kind in the US.

The four defendants declined to comment.

Modern Settings, a Florida-based maker of jewellery and police badges, said purchasers lost millions of dollars.

The Florida company filed the complaint in Manhattan federal court.

Platinum and palladium are used in jewellery, cars and dentistry.

The companies were accused of having conspired since 2007 to rig the twice-daily platinum and palladium fixings.

Front running

It is alleged that the companies illegally shared customer data and then used that information to engage in front running.

Front running is a form of market manipulation in which traders profit by using information about their clients' trading intentions.

Traders will often know how a particular client order will affect the market and can place their own trades ahead of that order to benefit.

The four companies in this case are also accused of manufacturing "spoof" orders.

New system

Last month , the London Metal Exchange said it will take charge of platinum and palladium price fixing, and use a new electronic platform from the 1st December.

However, the lawsuit said those changes "have come too late".

Goldman, HSBC and Standard Bank declined to comment.

A spokeswoman for BASF, the world's largest chemicals maker, said the group could not comment because it had not been notified of the complaint.

International regulators have tightened scrutiny of pricing benchmarks in recent years.

The tighter regulation comes after a currency trading scandal and the Libor scandal, which fixed a benchmark interest rate.