People found guilty of rigging wholesale gas and electricity prices could face up to two years in prison under new government proposals.
Currently regulators can investigate and fine people who have manipulated the market, but Energy Secretary Ed Davey said he wants to make it a criminal offence.
New laws would make it illegal to fix energy prices at an artificial level or use insider information to buy or sell energy on the wholesale market, with offenders facing a jail term and a criminal record.
The move is aimed at safeguarding consumers and providing a "stronger deterrent" against abuses, the Department of Energy said.
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Temperatures will be on the warm side tomorrow as much of the country looks forward to a fine bright start to the day.