Almost one million Australians will be able to enjoy half-price flights to domestic holiday destinations, under a government plan announced Thursday to boost tourism as Covid border closures keep international travellers out.

Prime Minister Scott Morrison said the government would spend Aus$1.2 billion (US$929,000 million) to subsidise 800,000 flights to areas outside major cities that were "heavily dependent on international tourists".

Half-price airfares will be offered to entice Australians to book holidays at places like the Great Barrier Reef, Uluru and the Gold Coast.

Australia has been effectively sealed off from the rest of the world since shutting its border last March in response to the coronavirus pandemic, and is yet to announce when it will reopen to overseas visitors.

International tourism was worth about Aus$45 billion (US$35 billion) a year to the country's economy before the pandemic hit.

A massive funding package subsidised millions of jobs over the past year but will finish at the end of March, raising concerns thousands of people in worst-hit industries like tourism will be left out of work.

The discounted airfares will be available from April, as the government looks to cushion the blow and put the onus on Australians to help support the sector.

Several lesser-known holiday spots typically more popular with locals than international tourists are also among the 13 supported destinations.

The initiative has been welcomed by struggling airlines Qantas and Virgin Australia, but others in the travel industry as well as workers' unions have complained it does not go far enough.

Morrison has called the scheme "a bridge to a more normal way of life for Australians", adding that tourism businesses "don't want to rely on government support forever".