Washington - The United States plans new curbs on derivatives markets, an unwieldy and lightly regulated portion of the financial industry that in part helped bring down the global economy, regulators unveiled Wednesday.

Treasury Secretary Timothy Geithner suggested that over-the- counter (OTC) derivatives, which include credit-default swaps that lie at the centre of the US mortgage downturn, should be traded on exchanges.

Many OTC derivatives are currently traded privately and have mostly avoided government regulation. Geithner said the move would help boost transparency and the pricing of assets.

A number of large financial firms were brought to the brink of collapse last September on mortgage-related derivatives that plunged in value as a decade-long housing boom ended in mid-2006. American Insurance Group, which insured credit-default swaps, is now being supported by 180 billion dollars in emergency government loans.

"All OTC derivatives dealers and all other firms whose activities in those markets create large exposures to counterparties should be subject to a robust and appropriate regime of prudential supervision and regulation," Geithner said in a letter to Congress.(dpa)