John Sharp issued the warning during a Senate inquiry into Commonwealth bilateral air service agreements last week - just days after Rex announced it would reduce services on eight of its regional routes.

The airline claimed the "relentless pillaging" of its pilots by major carriers, in particular Qantas, was to blame for the cuts.

Qantas has rubbished the claims, saying pilots apply for advertised positions and are not poached.

Sydney-Griffith, Sydney-Narrandera and Sydney-Albury SAAB-340 services are among those affected by the most recent reductions, which were revealed on September 22 and come into effect on October 30.

On the same day, Rex will expand its domestic network - serviced by larger Boeing 737-800NG aircraft - with the launch of new daily direct flights between Adelaide and Brisbane.

Mr Sharp, a former federal transport minister, told the Senate inquiry Rex's regional operation had suffered a loss of about $30 million a year because of "Qantas's predatory behaviour".

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"As a result of that, Rex have announced cuts and reductions to more than a dozen ports in an effort to reduce our losses, and we made an announcement just a few days ago [on September 22]," he said.

"I give this as an example of one of the ways Qantas behaves in a so-called competitive airline market. Their behaviour is designed to restrict competition, not to encourage it."

Rex has complained to the ACCC about the national carrier but the inquiry heard from Qantas's general counsel Andrew Finch that no evidence of such "predatory behaviour" was found.

When the most recent round of cuts comes into effect, Rex's Sydney-Griffith schedule will be reduced from five return flights each weekday to three, while the Sydney-Narrandera service will be reduced from three flights a day to two flights a day, Monday to Friday.

Sydney-Albury flights running from Monday to Friday will be cut from five return flights to three, with weekend schedules "being tweaked".

The airline said it had been forced to make further reductions across its regional network as the "major carriers, particularly the Qantas Group, continued their relentless pillaging of Rex's pilot group".

Mr Sharp told the inquiry this was another example of behaviour designed to restrict competition. He said Rex had lost 37 per cent of the pilots in its regional fleet and "the bulk of those have gone to Qantas".

A Qantas spokesman also rubbished that claim. The spokesman said the national carrier didn't poach pilots, rather it advertised for them in an open market and assessed applications for the positions.

Rex has two pilot academies - one in Wagga that can accommodate almost 200 students and another at Ballarat of almost the same size.

Mr Sharp told the inquiry the majority of the regional pilots the airline had lost were captains.

"As we train cadets ... they come out as first officers, but it takes four to five years to train them up to be a captain. So, when you lose a captain, you've got a long lag factor before you can replace them from within your own resources," he said.

When asked by committee chair Senator Bridget McKenzie what the government could do to resolve the issue, Mr Sharp said airlines that take pilots from another airline should have to pay a transfer fee, as is the case in some other countries.

He also said there should be a requirement for each airline to "invest in their future by training their own pilots rather than pinching everybody else's".

Mr Sharp said the airline could not afford to wait for the Commonwealth government's aviation white paper, a document outlining long-term policies for growth and innovation in the sector, to be released.

"If we have to wait for the white paper, which I suspect won't be until towards the end of next year, we'll have lost a lot of pilots, and we will be further reducing our frequencies and services in regional Australia," he said.

This story was originally published on The Daily Advertiser.