Prime Minister Anthony Albanese has dismissed suggestions he played a key role in protecting Qantas from extra competition.
In July, the Labor government rejected a proposal by Qatar Airways to add an extra 21 Australian routes - a bid that might have reduced airfares and boosted the tourism industry by $788 million.
The move came under scrutiny after it was revealed Qantas lobbied the government to do so before posting a record $2.5 billion profit over the 2022/23 financial year.
Under questioning about whether he met with Qantas CEO Alan Joyce, Mr Albanese told parliament he had one "extensive conversation" about the Qatar Airways deal, but it was not with any representative from Qantas.
"I received no lobbying from Qantas on this issue," the prime minister said during Question Time on Monday.
He said opposition questions about the arrangement came from "a complete failure to understand the way the international aviation system works".
"We have the most open aviation market in the world, bar none," he said.
"Qatar Airways can add more seats in Australia today, right now."
Mr Albanese noted when he was minister in 2009 he doubled Qatar's access from seven to 14 flights.
He said global aviation was not a free-for-all, giving the example of Australian carriers being limited in their access to European markets.
Nationals Senate leader Bridget McKenzie is pushing for an inquiry into the decision.
"It's very easy to assume that this government is continuing to run a protection racket for the most complained about company in our country," Senator McKenzie said.
"The Australian public deserves to know why you made (the decision), that it wasn't just a cosy, special relationship, that it wasn't just a dirty deal."
Opposition Leader Peter Dutton said there was a "murkiness" around the government's rejection of Qatar Airways, describing it as a "sweetheart deal" with Qantas.
The Greens have introduced a Senate motion that would compel the government to release documents about the decision.
Queensland Acting Premier Steven Miles said he hoped "common sense prevailed" and the Qatar Airways decision was reversed.
The calls come after a horror week for Qantas, which has been marked by a Senate grilling on delays, a potential $250 million fine, and the revelation CEO Alan Joyce had received more than $10 million worth of shares.
The Australian Competition and Consumer Commission is taking court action after the carrier allegedly advertised tickets for flights that had already been cancelled.
A Qantas spokesperson said the company would review allegations made by the consumer watchdog, but acknowledged its standards "fell well short" as the airline emerged from the COVID-19 pandemic.
"The ACCC’s allegations come at a time when Qantas’ reputation has already been hit hard on several fronts," the spokesperson said.
"We know it will take time to repair and we are absolutely determined to do that."