By Renju Jose and Lucy Craymer

SYDNEY/WELLINGTON (Reuters) - 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.

Airlines including Qantas, Emirates, Air New Zealand and Virgin Australia modified flight paths on Friday after China warned them about a rare live-fire exercise in international waters between Australia and New Zealand.

Both countries have raised concerns with China saying they did not receive adequate notice from China's navy about the military exercise off Australia's New South Wales coast.

Pilots are typically alerted to military drills, rocket launches and other issues that can affect airspace through Notices to Airmen, or NOTAMs, which are usually filed at least 24 hours in advance of such an event.

Airservices Australia CEO Rob Sharp told a parliamentary hearing late on Monday that a Virgin Australia pilot informed his agency that the Chinese navy planned to conduct a firing drill 300 nautical miles (483 km) off Australia's east coast.

"So that was how we first found out about the issue," he said.

Virgin Australia declined to comment.

The message from the Chinese was broadcast on an emergency radio channel monitored mostly by pilots and was then relayed to air traffic control officials, prompting them to issue an immediate warning for commercial airlines and set up an exclusion zone, Sharp's deputy Peter Curran said.

The live-fire drill could have started about 30 minutes before the Virgin Australia pilot first heard the message, and Australia's defence operations command was notified 10 minutes after air traffic control received it, Curran said.

The French defence forces, which conduct military drills near their territories in the Pacific, usually inform Australian air traffic 24 to 48 hours in advance, he added.

A People's Liberation Army Navy frigate, cruiser and replenishment vessel entered Australia's maritime approaches, and travelled down Australia's east coast last week.

China's defence ministry said on Sunday it had issued repeated safety notices in advance, and that its actions complied with international law and did not affect aviation flight safety.

Australian Prime Minister Anthony Albanese deflected a reporter's question about whether he was concerned a commercial pilot had to alert about the warnings from the Chinese navy task force.

"Australian defence were certainly aware and I've spoken with the chief of the defence force about what has occurred. Australia has had frigates both monitoring by sea and by air of the presence in the region of these Chinese vessels," Albanese told reporters on Tuesday.

Australia's defence department and the defence minister's office did not immediately respond to a request seeking comment.

New Zealand's military said on Tuesday the Chinese ships were currently 218 nautical miles east of Tasmania's state capital, Hobart.

(Reporting by Renju Jose in Sydney and Lucy Craymer in Wellington; Editing by Jamie Freed)