PARIS (Reuters) -Airbus is warning airlines that delays in deliveries will persist for another three years as it works through a backlog of supply chain problems, industry sources said.

The cautious tone on deliveries was reinforced at a recent customer gathering in Toulouse and increases pressure on Airbus to demonstrate progress towards a goal of increasing production of its main model to 75 jets a month, they added.

"Airbus is talking about delays to aircraft in both 2027 and 2028," a senior airline executive said, adding the delays were being communicated in piecemeal fashion every few months.

Another source said aircraft due for delivery later this decade had already been pencilled in for a six-month delay.

"There is no real sign of improvement," said a third person following a recent customer presentation.

"We are working together with suppliers to mitigate the impact of the current situation on our customers," an Airbus spokesperson said.