US lawmakers have overwhelmingly backed a bill that requires the nation's derivatives regulator to use its emergency authority to curb speculation in energy markets, even as the watchdog continues to stress that supply and demand, rather than trading, is driving record fuel prices.

The bill, passed by 402 votes to 19 in the House of Representatives, calls on the Commodity Futures Trading Commission to deploy existing powers, such as introducing position limits and higher margin requirements, to curtail swaps and bilateral trading in the energy futures markets.