Australians won't get to see proposed laws to rescue the country's ailing environment until they are tabled in parliament next year.
The draft laws were originally supposed to go before parliament by the end of this year but that has since been pushed back.
No date has been set and the new goal is as early as possible next year, a Senate estimates hearing has been told.
"It's as early as possible in 2024, but I can't give you more precision than that," environment department Deputy Secretary Dean Knudson told Monday night's hearing.
Greens Senator Sarah Hanson-Young said that was a surprise "because a month ago we were told it would be March".
Environment department Secretary David Fredericks told senators the incredibly complex nature of the task had become apparent.
But the government was proceeding in good faith, and offering early consultations with key stakeholders.
"We could wait for the perfect piece of draft legislation to put out, but it might be a long wait," he said.
"We want to engage early and well, not late, so we've prioritised early engagement. It's not perfect. At the end of the day, it's a massively complex piece of legislation ..."
But there is anger among some over plans to restrict early consultation to about 30 groups representing conservation, business, mining, property and Indigenous interests.
They will get a first look at some aspects of the proposed laws in Canberra next week, and up to four opportunities to review and comment between now and early next year.
But even those groups will have limited access.
They will be able to review material in person, in Canberra, but won't get copies and will have to take notes if they want to share any details.
Senator Hanson-Young questioned why such important reforms were being dealt with via "secret documents" in a "secret meeting", with groups denied actual documentation and told to take notes.
Mr Knudson said there was nothing secretive about the government's approach.
He said the government wanted groups to consult with their wider circles, but the draft material wasn't ready to be shared.
Environment Minister Tanya Plibersek had brought consultations forward to get "early soundings" from key organisations.
"The quid pro quo on that is that we're sharing our thinking at this point. That is not at the point where that would be fully out in the public domain," he told the hearing on Monday night.
Senator Hanson-Young replied: "This is all just cover for the fact that you're running 18 months behind schedule."
The groups invited to participate in early consultation include the Australian Conservation Foundation and WWF Australia, the Minerals Council of Australia, the National Farmers Federation, and the Property Council of Australia.
James Tregurtha, the head of the environment department's nature positive taskforce, said they would get to see draft national environmental standards next week.
Those standards are the centrepiece of the new laws, and will describe the outcomes they should achieve.
Detail will also be provided about the regulatory, assessment and approval system, Mr Tregurtha said.
The draft legislation would be put up for consultation in tranches, with invited groups to have up to four opportunities to comment between now and early next year.
Mr Knudson said the order reflected the concerns of stakeholder groups.
"For example, there are provisions on wildlife trade in the legislation which are not exactly seizing the nation," he said.
"Some stakeholders care deeply about those, and we'll engage on those at the back end.
"What we've heard from stakeholders is that they're wanting to engage principally. When I say that, I'm talking about the large NGOs and the large business groups wanting to talk about the approvals and assessment system. So that's where we're starting ..."
The environment minister has promised the general public will get their chance to comment on the proposed laws, in the standard way.
