PARIS - European planemaker Airbus has ordered suppliers to demonstrate as soon as possible that they are factory-fit for increased single-aisle jet output, in a letter that lays bare the extent of recent industrial quality problems.

In the letter to suppliers in late March, seen by Reuters, Chief Procurement Officer Juergen Westermeier gave no specific targets but called for "immediate actions" to prepare for higher output, in the latest evidence of a recovery for mid-range jets.

Airbus declined to comment on contacts with suppliers.

Reuters reported last week Airbus had told suppliers to be ready for output of 53 A320neo-family jets a month by the end of 2022, up from current monthly output of 40 and a target of 45 by end-2021.

Airbus has declined to comment on goals beyond 2021. But underscoring advanced planning for higher output, Airbus urged suppliers in the letter to "demonstrate rate and capability readiness as early as possible."

Airbus also warned suppliers over quality-control problems that have disrupted factories or affected airline operations.

In 2020, Airbus experienced 370 quality problems from suppliers, equivalent to 1.6 per day, of which half had some impact on aircraft, the letter said.

"We are still facing too many issues ... We count on you to secure with rigour and discipline a much better containment and prevention plan," the letter said, adding: "Our first priority is to raise the bar on quality."

U.S. rival Boeing BA.N is also wrestling with production quality problems on best-selling models. 

Airbus operates one of the world's most valuable supply chains, with 8,000 direct suppliers and 18,000 indirect ones providing millions of parts worth some $50 billion a year.

(Reporting by Tim Hepher. Editing by Jane Merriman) ((tim.hepher@thomsonreuters.com; +33 1 49 49 54 52; Reuters Messaging: tim.hepher.thomsonreuters@reuters.net))