Qantas has announced it is cutting 108 maintenance jobs from Sydney.

Of those positions, 72 will be relocated to Melbourne, but 36 will be lost altogether.

The airline says Sydney workers who have lost their jobs will have the option to move to Melbourne.

It says the positions will also be offered to workers at the Qantas heavy maintenance facility in Melbourne, which is due to close in August.

Glen Thompson from the Australian Manufacturing Workers Union says the move is part of a concerning trend.

"Not even four weeks ago 400 people lost their jobs. This has created a whole lot of uncertainty for workers within Qantas," he said.

"And more concerning for us is the vision that Qantas has got in respect to Qantas engineering.

"We're wanting Qantas to come clean on what it is their views are for engineering going forward."