The Socialist-led government is in talks with Alstom to prevent the company transferring manufacturing from the plant, which made France's first high-speed trains as well as the company's first steam engine in 1880.

"I just heard from the Finance Ministry that Sept. 30 has been set for presenting a plan, not only for Belfort but for Alstom in general," as Force Ouvriere union official told Reuters. "The plan will cover all of the sites whether it be assembling or manufacturing component."

Alstom unleashed a political storm seven months ahead of a presidential election when it said earlier in September that it would stop producing trains at the site in eastern France and transfer more than 400 workers to other plants in the country.

Alstom, which is 20 percent controlled by the state, said the move was necessary as it had a gap in orders from 2018 for the plant, which makes passenger, freight and high-speed locomotives.

Government officials have raised the possibility of bringing forward contracts already in the pipeline, such as an order for high-speed trains for the Paris-Milan route.

Government spokesman Stephane Le Foll said earlier on Wednesday that progress was being made and an announcement would be possible next week.

(Reporting by Emmanuel Jarry and Simon Carraud; writing by Leigh Thomas; editing by Richard Lough and David Clarke)