Qantas has rejected Airbus and Boeing’s proposals for new aircraft that can fly non-stop from Sydney and Melbourne to New York and London, saying they need to lower their prices to make the business case stack up.

The airline has said it will make a decision by the end of this year on whether or not to launch its so-called "Project Sunrise" flights and is looking to buy either Boeing 777-8Xs or Airbus A350-100ULRs to operate what will become the world's longest commercial flights.

Qantas's second "research flight" arrives in Sydney on Saturday after flying non-stop from London. Credit:Mark Metcalfe

Airbus and Boeing had submitted their "best and final offers" on their planes to Qantas in August. But Qantas said on Tuesday it had sent the aerospace giants back to Toulouse and Chicago to reconsider those offers.

“We’ve asked them to go back and re-look at that, to sharpen their pencils, because there still was a gap there," Qantas International chief executive Tino La Spina told an investor briefing in Sydney on Tuesday.