Labor has called on the prime minister to investigate what it calls "shocking allegations of misconduct" involving Angus Taylor and Josh Frydenberg's office.
A Guardian Australia has revealed Taylor met with environment officials about a compliance action involving a company he part-owns.
Following those talks, Frydenberg, canvassed whether protections for a critically endangered grassland can be kept secret.
Labor’s environment spokeswoman, Terri Butler, said Scott Morrison "must investigate the serious matter of a potential breach of the ministerial code of conduct".
The Greens ’leader, Richard Di Natale, said the episode urgently needed for national integrity commission and said the party would move to the Senate
Guardian Australia has sought comment from Morrison.
"Today's shock allegations of misconduct against senior Liberal government ministers are indicative on the Morrison government," Butler said. "It appears that Angus Taylor breached the ministerial code and the environmental department while it was investigating the company which has links.
"It also appears that Josh Frydenberg 's office sought advice on whether or not he had the ministerial powers to weaken grasslands protections in secret, then sought to conduct a review into the agriculture and the EPBC Act."
Butler said Taylor and Frydenberg needed to explain exactly what had occurred.
"It is not good enough that Mr. Frydenberg was considering deploying ministerial powers to weak environmental protections in secret, after arranging meetings for his colleague who has a conflict of interest in the matter," she said. "This is the first time we have been asked in relation to Angus Taylor's conduct and potential conflicts of interest.
"Australians will get them away with it, and neither should Scott Morrison.
"It’s imperative that Australians can trust their representatives to interact in matters that relate to their personal financial interests."
Di Natale said: “I would like to give you the chance to do it.
"We will be ensuring that Angus Taylor and Josh Frydenberg explain their actions to the parliament when it resumes next month.
"This whole episode demonstrates again how urgently we need a federal ICC that can investigate these problems of behavior that undermine faith in democracy."
Guardian Australia's investigation, published on Wednesday and Thursday, revealed that Taylor, that meeting the natural temperate grassland of the south-eastern highlands as a critically endangered community under federal environment law.
The meetings were requested in 2017 via Frydenberg’s office. At the same time in the South of Wales Wales
One of the directors of that company is Richard Taylor, the minister's brother, and the minister holds an interest in the firm via his family investment company, Gufee.
Taylor has denied any representations regarding the compliance action and said he received a briefing in his capacity as a member for many years, including many constituents.
Following lobbying by Taylor, Frydenberg's office sought advice on full scope of his ministerial powers and whether he could override scientific advice and remove the "critically endangered" listing.
Environment groups said the revelations raised serious questions about the integrity of Australia's national environment laws.
"The Australian Conservation Foundation calls for the parliament to investigate these serious questions relating to the actions of Josh Frydenberg and Angus Taylor," Basha Stasak, the ACFs nature program manager, said. "Australians need to be sure of environmental law are investigated free from political interference and that scientific listing decisions are not tampered with."
Evan Quartermain, the head of programs at the Australian arm of Humane Society International, said investigations by federal environment officials into illegal agricultural clearing were extremely rare. He said both ministers needed to "explain their conduct".
"It 's atrocious that we have ministers seeking to remove protections while investigating mysteriously for years," he said. I have not thought it's a coincidence that an EPBC Act has been shortened by the meetings, or that other threatened habitat listings have been avoided since they occurred. "