Qantas says an investigation into financial losses at the airline's franchise in Vietnam, Jetstar Pacific, is preventing two Australian executives from leaving the country.
Chief operating officer Daniela Marsilli and financial officer Tristan Freeman are being questioned in relation to losses on petrol reserves.
Former chief executive Luong Hoai Nam was arrested in Hanoi on Thursday in connection with a $A34 million loss on fuel hedging contracts.
Qantas chief executive Alan Joyce says the Australians cannot leave the country because they're being questioned about their role in the loss.
The ABC reports the Department of Foreign Affairs & Trade raised the matter with Vietnam's ambassador to Australia on Christmas Eve.
Mr Nam resigned as chief executive in November and was at the helm of the company at the time of the losses.
Jetstar Pacific started flying under the Jetstar brand in May 2008.
Qantas owns nearly a third of the airline and an investment arm of the Vietnamese government holds the majority stake.