Air New Zealand has hit out at what it says are malicious rumours, which suggest the airline has been flying unsafely since a volcanic eruption in Chile sent ash into the air.
Chief executive Rob Fyfe says false rumours have emerged from Australia alleging some of Air New Zealand's aircraft have been damaged by ash.
In an internal Air New Zealand staff memo, Rob Fyfe says it is complete fiction that ash damaged some of its aircraft and grounded a plane in Australia.
Mr Fyfe also says Qantas sent an email to customers justifying its decision not to fly and implying it was dangerous for airlines to fly.
He says Qantas did not mention it had transferred thousands of its customers on to Air New Zealand and other airline.
Mr Fyfe says Air New Zealand has borne a higher fuel cost by flying at a different altitude, and other airlines in Australasia are also continuing to fly.
Qantas is denying that it has implied that other airlines are operating unsafely by continuing to fly while volcanic ash is still in the air.
Qantas says no-one at the company, including Qantas chief executive Alan Joyce, has said or implied that other airlines are operating unsafely.
It says it has simply stated the airline's own policy and noted that other airlines have their own processes.
Qantas says it has also had to defend itself against cynical suggestions that cancelling flights is somehow a cost-saving measure, when safety has been the only factor in its decisions.