The State's consumer watchdog has refused to join a Government monitoring group overseeing the ending of flat rate waste collection.

The Competition and Consumer Protection Commission has also cast doubt on the effectiveness of the group, saying a more robust regulatory regime may be needed.

The Department of the Environment says the commission's decision is disappointing but insists the new monitoring unit will ensure there is no price gouging.

In a letter to the Department of the Environment, the CCPC says it cannot take part in the group because it would compromise its independence as an enforcement body.

However it goes on to say that "the attitude and actions of some operators" in the past gives rise to consumer protection and competition issues in the household waste market, and that the new unit may not have enough financial information to make a proper assessment.

The Government had announced that a price monitoring group would be set up to ensure that consumers were not subject to price hikes with the introduction of a pay-by-weight element.

This was agreed by Minister for Communications, Climate Action and Environment Denis Naughten as part of a compromise with Fianna Fáil, who had wanted the establishment of a regulator for the industry.

The flat fee system applies to nearly half the country's waste customers - mainly in Dublin - but the Dept of Environment announced that this was to be phased out as part of a move to encourage waste reduction.

New permits will be issued to waste companies over the coming weeks and after that, new contracts that are agreed over the following 12 months will not be allowed to contain flat rate fees.

The CCPC says it informed the Department of the Environment of its decision not to participate in the monitoring group on 25 August.

According to the letter which was released by the commission, the new monitoring group will be excluded from having information on waste companies' costs and states "excluding cost data militates against any objective assessment as to the reasonableness, or otherwise, of any price increase imposed on consumers".

It also says the terms of reference would not provide the monitoring group with pricing history, making it difficult to identify any recent price increases made in anticipation of the ending of flat fees.

The CCPC was also tasked by a Dáil motion last July with reporting on whether a regulator was needed for the industry.

In its letter, the commission states that compiling this report may be "problematic" given concerns about the availability of historical pricing data.

It also says participation in the price monitoring group would be problematic in making an independent assessment of the household waste collection market.

The Department said in a statement that it is disappointed with the commission’s decision.

However it says the unit has been set up with independent economic experts, CSO analysts and representatives from St Vincent De Paul.

The Department says the unit's work will be publicly available and will ensure there is no price gouging.

Fianna Fáil's Environment spokesperson Timmy Dooley said the Commission's criticism signals the death knell of the Government's pricing monitoring unit.

He said: "What's now needed is an independent regulator to ensure an effective competitive environment exists in the waste collection market place to prevent householders being price gouged by unscrupulous waste collectors."