Julian Morgan, managing director of the business electricity price comparison, switching and advice serve for energy users, said it was only fair that customers benefit from lower wholesale energy prices.
"It's now time for the energy regulator to consider putting pressure on suppliers to pass on some of these savings to customers," Mr Morgan said.
"There is no evidence that suppliers intend doing this of their own accord, nor are they making any attempt to explain why not.
"Customers deserve better. Suppliers are quick-off-the-mark to raise their retail prices when the wholesale cost of energy rises, but very slow indeed to react when wholesale prices fall.
"Customers who are struggling to power their homes and businesses pay the price when the wholesale cost of gas goes up. It's only fair they should benefit when it falls."
This week, OFGEM said that gas prices for next day delivery reached their lowest level in almost four years at the start of June, and are 38% lower than this time last year.
Prices for electricity reached their lowest level since April 2010, and are currently 23% lower than June 2013.
Read more about 'Energy Advice Line joins call for price cut' here