Following the claims of price-fixing in the gas market, a trader told ITV News that electricity prices may have been manipulated in the same way.
Today the Energy Secretary said companies caught breaking the rules would face the full force of the law - to protect consumers.
Watch Business Editor Laura Kuenssberg's report:
Read Laura Kuenssberg's blog for more.
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.