Unions are against an impending Qantas/Emirates partnership, arguing it's a bad move for their members and airline customers.
AAP reports the Australian Consumer & Competition Commission is holding a conference on the proposal on Friday.
Transport Workers' Union national secretary Tony Sheldon said he will reiterate that the partnership is a bad deal on many fronts.
"It's bad for consumers, it's bad for the travelling public, it's bad for the economy and it's bad for the Australian workforce," he said outside the conference in Sydney.
"Shrinking Qantas and handing over our national routes is putting our economic future into the hands of a Middle East carrier in a volatile part of the world."
Senator Nick Xenophon, who is also giving evidence, said the deal would mean further job losses.
"We will see a shrinking of the flying kangaroo and further job losses," he said.
Earlier this month the ACCC gave Qantas and Emirates approval to prepare joint strategies for sales, marketing and pricing.
But the ACCC also said its interim authorisation of the partnership may be reviewed at any time and should not be seen as an indication of whether final approval will be given or not.