Federal Labor is again circling senior government figures over a 2017 meeting about environmental regulations.
Labor has been targeting Energy Minister Angus Taylor over his interest in a family company, Jam Land Pty Ltd, linked to an investigation into alleged illegal land clearing and endangered grasslands.
The opposition's pursuit centres on a 2017 meeting with environment department officials and the office of then-environment minister Josh Frydenberg.
It was held while investigations were underway into the alleged poisoning of 30 hectares that contained the grassland on a NSW property Jam Land Pty Ltd owned.
Mr Taylor maintains he disclosed everything according to the rules, and on Sunday said Mr Frydenberg was aware of his interests ahead of the meeting.
"My obligation is to disclose to the parliament and to the prime minister," he told ABC's Insiders program.
"The minister, which was Josh Frydenberg at the time, was also aware, so there was no lack of disclosure and compliance on this."
But Mr Taylor said he wasn't aware of any compliance actions and was advocating for farmers in his electorate.
"I will do it every day of the week because they need representation on issues like this," he said.
Environment department bureaucrats recently told a Senate inquiry - which was looking at a separate issue - they knew Mr Taylor's brother owned the land being investigated.
But the compliance issue wasn't raised in the meeting, they added.
Labor MP Chris Bowen says Mr Frydenberg must explain if he knew of his colleague's interests.
"He has to explain why he got his department to come into a meeting about a private interest of a member of parliament, which he was fully aware of," Mr Bowen told reporters in Sydney.
"One of these ministers, one of these men, has to explain their actions."
In response, Mr Frydenberg on Sunday repeated what Mr Taylor told parliament, saying that his interest in Jam Land was declared in accordance with the rules through his family company.
Labor is concerned the minister didn't properly disclose his interest in the company, pointing to department answers to Senate committee questions and a freedom of information request that show no records of the minister declaring his interest in Jam Land to the bureaucrats.
Australian Associated Press