Australia air force pilots also heard Chinese navy live-fire warning on radio

AVALON, Australia (Reuters) - The Royal Australian Air Force (RAAF), monitoring a Chinese navy warship as it circumnavigated Australia last month, heard it warn it would use live fire in its exercises on a civilian radio broadcast, defence pilots said on Tuesday.

A People's Liberation Army Navy frigate conducted the unprecedented live-fire exercise in the Tasman Sea between Australia and New Zealand in February, causing 49 commercial flights to be rerouted.

China has said it gave adequate warning about the drill under international law, but Australian and New Zealand authorities said it fell short of best practice for notifications.

Commercial airlines first heard about the live-fire drill when a Virgin Australia pilot picked up a Chinese navy broadcast on the 121.5 MHz emergency radio channel.

Ahead of a national election due by May, opposition Liberal Party leader Peter Dutton criticised the Labor government for "a situation where our national maritime surveillance was outsourced to a Virgin airline pilot".

At the Australian International Airshow in Avalon on Tuesday, RAAF maritime surveillance pilots said Australia's P-8A Poseidon were flying "high duration, high frequency sorties" and monitoring the Chinese navy warship's transmissions on UHF and VHF at the time, in details that had not previously been made public.

"The transmissions that came through are just standard warnings of their positions as well as their intent of live-fire exercises," said P-8A Poseidon flying officer Patrick Makeham.

He described this as "similar to saying that we will be conducting live firing exercise in those areas".

Air Commodore Gus Porter, director-general of RAAF air combat capability, said the P-8A aircraft were used for anti-submarine warfare and to deter aggression.

"You don't need to be on top of a task group 24 hours a day to be tracking exactly what they are doing," he added.

The RAAF P-8A aircraft conduct routine surveillance patrols in international waters in the South China Sea, which China has criticised.

Australia last month complained to China over what it was "unsafe and unprofessional" actions by a Chinese fighter jet releasing flares within 30 metres (100 feet) of an Australian P-8A aircraft.

(Reporting by Kirsty Needham in Avalon, Australia; Editing by Jamie Freed)