Australia learned about Chinese live-fire naval drills off the country’s coast that forced dozens of flights to be diverted via an alert from a commercial pilot, authorities said on Monday.

The Chief of the Defence Force, David Johnston, told Senate estimates on Wednesday that a warning from a New Zealand warship that Australia was relying on to track the flotilla was ­received in Canberra about 11am last Friday – 90 minutes after the exercise began and about an hour after a similar warning was ­relayed by a commercial pilot.

A Virgin Australia pilot alerted Australian authorities about a live-fire drill by Chinese naval ships last week in the Tasman Sea that forced 49 flights to change their paths, Australia's air traffic control agency head told a parliamentary committee.

China's military failed to inform the Australian Defence Force it would be conducting "irresponsible" live-fire drills, which posed a risk to civilian aircraft.

Dozens of commercial flights had to change course last week when they were surprised by Chinese naval drills off the coast of Australia. But China said its navy repeatedly issued notices.Some 49 commercial flights were forced to change course last Friday when Chinese warships unexpectedly announced naval drills off the eastern coast of Australia,