Shadow energy secretary Caroline Flint said:
These are very concerning reports which, if true, suggest shocking behaviour in the energy market that should be dealt with strongly.
For months, Labour has said that customers are getting a raw deal and the gas and electricity companies should be forced to sell the energy they generate into a pool, to open up the market and ensure fairer consumer prices. These reports make the need for action all the more urgent.
A former energy trader has told ITV News the electricity market has been rigged and it is "worse" than the gas market.
Another market, another investigation. The Energy and City watchdogs start investigations into allegations of traders fixing the gas price.