Australia's environmental sector wants the Turnbull government to explain its plans for significant changes to major programs, including savings of more than $350 million from axing the Green Army - Tony Abbott's much-hyped employment project.

Environment and Energy Minister Josh Frydenberg all but confirmed reports on Monday that the government's Expenditure Review Committee had decided to kill off the program in this month's budget update, saying savings were required from across government.

Established after Mr Abbott's 2013 election victory, the Green Army was designed to use the manpower of up to 15,000 unemployed young people, aged 17 to 24, for conservation projects in every state and territory.

Prime Minister Malcolm Turnbull said he wouldn't comment on the project's demise before the mid-year economic and fiscal outlook statement, due on December 19.