PARIS - France urged Airbus and flag carrier Air France on Wednesday to make as few forced layoffs as possible under their plans to cut thousands of jobs, while a union said compulsory cuts at the European planemaker were a "red line".

The aerospace manufacturer said it would cut 15,000 jobs in Europe in a restructuring after a 40% slump in its 55 billion euro ($61.8 billion) jet business, sparking concerns about compulsory redundancies in France where it has its headquarters. 

Junior Transport Minister Jean-Baptiste Djebbari said the government estimated 2,000 of 5,000 planned cuts by Airbus in France could be saved by a reduced-work scheme and with help from state investment in next-generation green jets. 

France's hard-left Force Ouvriere union said mandatory job cuts at the planemaker were a "red line" and other labour representatives said they would fight such measures.

Workers told Airbus to focus on voluntary departures or retirement plans.

"The state urges Airbus to ensure that there are as few forced redundancies as possible," Djebbari told BFM TV. "Airbus faces a very difficult period ahead. The state stands beside Airbus, and beside Air France."

Djebbari urged Air France, which also plans layoffs due to the travel slump, to minimise compulsory redundancies, after the government agreed state aid for the carrier worth 7 billion euros ($7.9 billion).

"It's not 7 billion euros to pay for redundancy programmes. It's 7 billion for survival, to pay salaries at the end of the month," the minister said.

Djebbari confirmed Air France planned to shed nearly 7,600 jobs in a restructuring plan to be announced this week, including 1,000 at its regional unit 'Hop!'. 

Force Ouvriere called on Airbus to press on with plans to bring some assembly operations for the A321 aircraft to the French city of Toulouse, where the group has its headquarters.

Airbus has been striving to balance belt-tightening against aid offered by European governments to survive the coronavirus crisis. Djebbari said it was too early to say whether some Airbus plants might close.

The French government, which owns 11% of Airbus and 14.3% of Air France KLM, has asked Air France to cut carbon emissions and domestic flights as conditions for state financial support.

($1 = 0.8909 euros)

(Reporting by Sudip Kar-Gupta, Richard Lough, Myriam Rivet and Sarah White; Editing by Louise Heavens and Edmund Blair) ((sudip.kargupta@thomsonreuters.com; +33 1 49 49 53 84;))