Deputy Prime Minister Barnaby Joyce says a letter from a former head of his department expressing a lack of confidence in him didn't deserve to be made public.
In the 2015 letter, which has been kept secret for more than a year, former agriculture department boss Paul Grimes tells Mr Joyce he no longer had confidence in the minister's capacity to "resolve matters relating to integrity" with him.
Their dispute relates to ministerial changes to the parliamentary record in which Mr Joyce and the department became embroiled.
In his first public comments on the matter, Mr Joyce admits the pair just didn't get along.
It happened during a "tough" period when negotiations for the agriculture white paper were taking place.
"It's quite obvious that the relationship had fallen into basically a point of no return," he said in Canberra on Wednesday.
The Nationals leader claims Dr Grimes later tried to retract his words and that's why the letter shouldn't have been published.
"What he reflected to in that letter - which he later wished to withdraw - I didn't think deserved to be put out there.
"But the decision was never mine - it was the secretary of the department's decision."
Dr Grimes was stood down just over a week after sending the letter.
Labor says it's clear that the bureaucrat was first bullied, then sacked for trying to protect the reputation of the department.
Mr Joyce denies this, saying the termination was a decision for the department of then-prime minister Tony Abbott.
"I don't dismiss him - the secretary of PMC is part of that."
Labor also claims the saga has cost taxpayers almost $1 million as the department fought the publication of the document.
A spokesman for Mr Joyce says the legal fees amounted to $35,000.
