In an announcement to the Australian Stock Exchange (ASX), Virgin said it planned to keep operating flights despite handing over the keys to administrators.

"Our decision today is about securing the future of the Virgin Australia Group and emerging on the other side of the Covid-19 crisis," CEO Paul Scurrah said in the statement.

"Australia needs a second airline and we are determined to keep flying."

The airline was more than A$5 billion (US$3.2 billion) in debt and had appealed for an A$1.4 billion loan to stay afloat, but the government refused to bail out the majority foreign-owned company.

The airline said four insolvency experts from accounting firm Deloitte had been appointed as administrators.

"Our intention is to undertake a process to restructure and refinance the business and bring it out of administration as soon as possible," administrator Vaughan Strawbridge said.

"We have commenced a process of seeking interest from parties for participation in the recapitalisation of the business and its future, and there have been several expressions of interest so far."

Virgin had already stood down 8,000 of its 10,000 staff, suspended all international routes and scrapped all bar one of its domestic routes after Australia shut its borders to limit the spread of Covid-19 and imposed tough restrictions on movement.

Richard Branson, the billionaire founder of Virgin Group, which owns a 10-percent stake in the airline, tweeted a message in support of the Virgin Australia team.

"I am so proud of you and everything we have achieved together," he said.

"This is not the end of Virgin Australia, but I believe a new beginning. I promise we will work day and night to turn this into reality."