The NSW treasurer has rejected a rogue MPs claims as "fantasy" after she said he called himself the greatest environment minister in Australian history during an argument over koala policy.
Outgoing Liberal MLC Catherine Cusack told the NSW parliament's upper house on Wednesday the government's koala policy is accelerating the destruction of their habitat.
Ms Cusack also said former environment minister and now Treasurer Matt Kean told her he was "one of the greatest - probably the greatest - environment ministers in Australian history".
Ms Cusack posted a series of screenshots of text messages on Twitter this week showing former premier Gladys Berejiklian urging her to support the policy during the coalition's "koala wars" in 2020.
Ms Cusack later crossed the floor and voted against the policy, leading to its defeat.
Mr Kean rejected the claims from Ms Cusack, including that a deal was done between the Liberals and Nationals during the so-called koala wars.
"I would just like to say that I wholeheartedly reject the recollection of events by Ms Cusack," the treasurer said during question time on Thursday.
"I think it's clearly some wild fantasy that's been dreamed up late at night."
Premier Dominic Perrottet also defended Mr Kean's record, saying the state was leading the country on the environment.
"In an area where the Liberals and Nationals are not seen to be leaders when it comes to the environment, I think ... our state, is by far the best in the country," he said on Thursday
"A lot of that is testament to these policies and of minister Kean. We've done more to protect koalas than any government before us."
The government spent four years developing its koala State Environmental Planning Policy, and while trying to pass the legislation endured a bruising stoush that looked to destabilise the Liberal-National coalition.
Ms Cusack said she believes the government's current koala policy is dysfunctional.
"The NSW Koala Strategy is based on the idea that we can buy our way out of the problems created by private native forestry, native forest and native vegetation clearing -- which is accelerating destruction by a factor of three," she told the upper house Wednesday.
"The plan sees volunteers and wildlife funds planting and revegetating areas for the future, while across the road established trees that are being used by koalas are being cut down - and it is subsidised by taxpayers.
"This is sheer madness."
Ms Cusack made the comments while supporting the Greens' Great Koala Protected Area Bill, which was defeated in the upper house on Thursday.
Labor's environment spokesperson Penny Sharpe said Ms Cusack's speech had exposed the government's hubris over koala conservation.
"As we stand here today in NSW now, koalas that live in the wild are on track to be extinct by 2050," Ms Sharpe said.
She said Labor was committed to improving koala numbers and would deliver a fully costed plan ahead of the 2023 state election.