Australia's government Thursday cited Qatar's "invasive" searches of women air passengers three years ago as a factor in its decision to block extra flights by the nation's airline.

Women passengers on a series of Qatar Airways flights from Doha -- including one bound for Sydney -- were subjected to gynaecological examinations in October 2020 as the authorities searched for the mother of a newborn baby found in an airport bathroom.

The women had been escorted at gunpoint from their planes for "invasive searches" in ambulances on the tarmac, Transport Minister Catherine King reminded reporters as she explained her decision to reject the carrier's request for 21 extra international flights into Australia.

King said she decided on July 10 to refuse the Qatar Airways request for more flights to Sydney, Melbourne and Brisbane in the "national interest".

"For context, this is the only airline that has something like that," she said of the 2020 body searches, which sparked international outrage.

"That has happened and so I can't say I wasn't aware of it. But certainly it was not the only factor."

Opponents accuse the centre-left Labor government of trying to shield Australian carrier Qantas from competition despite its record profits, resulting in high fares for international flights.

"There was no one factor that influenced this decision," she insisted.

King said Qatar Airways, which operates 28 international flights a week into Australia, could boost international flights to Canberra and other regional airports.

Five women are suing Qatar Airways and the state-run Qatar Civil Aviation Authority over the 2020 gynaecological examinations.

Australia's national broadcaster ABC said King had written a letter to the five women on the day of her decision on the Qatar Airways flights, saying she was shocked by the "disgraceful" treatment they had been subjected to in Doha.

The Qatar embassy in Canberra has been asked for its response to the minister's comments.