Some of the biggest players in Australia's carbon market say the system needs to change. 

The companies that collectively generate a majority of Australian Carbon Credit Units (ACCUs) through ‘Landfill Gas’ methods have signed letters saying the credits are often issued for actions the industry would take anyway.

An even larger group of companies representing nearly 90 per cent of the Landfill Gas carbon credits generated and more than a quarter of all green credits of all sorts say fewer credits to be given to the industry.

They say the overall integrity of the carbon credit scheme is being undermined.

The letters were sent to Ian Chubb, who is conducting an independent review of the scheme for government, and independent Senator for the ACT David Pocock.

Senator Pocock says he may look to block some of the newest forms of credits in the Senate before projects are locked into using them for decades.

John Falzon - chairman of LMS Energy - alongside bosses from a range of competitors including Cleanaway Waste Management and Veolia, say fewer carbon credits need to be handed out to companies like theirs.

“If the market doesn't have integrity it'll crash, so the business itself will collapse with that,” he told reporters.

“For us to have integrity is vitally important.

“We would forgo some short-term revenue for the opportunity to participate in a market that is more robust and has more credibility and that provides a future.”

The industry letters follow revelations by former Clean Energy Regulator insider-turned-whistleblower Andrew Macintosh, who has strong criticisms of several types of carbon credits.

“The government effectively was handing them a very large cheque for doing stuff that they would have done anyway,” he recently told reporters.

“And it takes big people with high integrity to say; ‘No, I'm not going to accept that, I want the method to have integrity’.”

The Clean Energy Regulator continues to defend the system it oversees.