Singapore Airlines yesterday angrily rejected as offensive claims by air traffic controllers that its pilots did not understand the correct procedures in areas left unsupervised because of the shortage of controllers.

Civil Aviation Safety Authority chief executive Bruce Byron confirmed yesterday that CASA would quiz foreign pilots on their understanding of the procedures as part of checks routinely carried out on foreign carriers.

Mr Byron said the regulator had increased the "ramp checks" significantly over the past 12months for issues related to airworthiness.

"But what we're taking is the opportunity, when we're doing that, to check to see whether the crew are familiar with these procedures," he said.

The Australian on Tuesday revealed claims by air traffic controllers that they often had to brief foreign pilots mid-flight about the measures they must follow in unsupervised Australian airspace - a situation they described as "a disaster waiting to happen".

Aircraft in areas with no air traffic control use a procedure known as Traffic Information Broadcast by Aircraft (TIBA) that relies on radio transmissions to work out the aircraft positioning.

The air traffic controllers' union, Civil Air, has called for a wholesale review of the safety procedures for passenger jets in uncontrolled airspace, amid claims - disputed by the controllers' employer, Airservices Australia - that the number of instances of uncontrolled airspace rose by 63 per cent in June.

Although CASA rejected the controllers' call, a spokesman confirmed last night that the increased checks of foreign pilots would start today.

The spokesman said the regulator would write to foreign airlines pointing out that TIBA was being used in Australia and asking them to refresh their knowledge of the procedure.

He said CASA would boost the frequency of the checks already being carried out on Airservices' Brisbane and Melbourne operations centres.

Singapore Airlines said it would not operate in an airport or airspace that was unsafe.

It said it followed internationally recognised procedures in those areas without air traffic control, and its aircraft were equipped with the highest standard of safety equipment, including collision-avoidance systems.

"Our pilots are trained to the highest internationally recognised standards, and suggestions they would compromise safety in controlled or uncontrolled airspace, whereas pilots for Australian carriers would not, are both false and professionally offensive," Singapore Airlines said.

"Indeed, our pilots are trained at world-class facilities, including two flying colleges in Australia -- at Jandakot (in Western Australia) and Maroochydore (in Queensland) -- which are recognised by the Civil Aviation Authority of Singapore and CASA."

The airline said it had been caught up in a series of claims and counter-claims arising from the industrial dispute.