Mr Whittle made the comments after the Resolution Foundation released recommendations for a voluntary code of practice to be implemented by comparison sites in an effort to build on their strengths.
He explained: "The sites do much more than promote switching between suppliers; they play a big part in driving price and customer service improvements by arming consumers with the information they need to make informed choices."
The latest comments from energywatch follow its criticism of a recent report by the UK's regulatory body.
According to the watchdog, Ofgem's review of fuel poverty schemes failed to identify recommendations on what can be done to improve energy suppliers' deals for low-income households.
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