Derby City Council is seeking talks with train builder Alstom over reports it could be about to lay off workers.
The firm's Litchurch Lane site is the only UK train factory able to design, build, engineer and test trains for domestic and export markets.
About 2,000 people work at the factory but the firm says its current order book only runs until early 2024.
The council said it was "shocked" to see reports of potential job losses and wanted to give any support it could.
Newspaper reports said the company had been relying on existing orders from HS2 but as these have been pushed back it was now looking to reduce its workforce.
It is estimated, as well as the core jobs, the factory also supports 1,400 supply chain companies employing about 17,000 people.
While it has its origins in the Industrial Revolution, the facility most recently supplied the fleet of 70 trains for the Elizabeth Line on London's Crossrail network.
Baggy Shanker, leader of Derby City Council, said the firm was one of the city's largest private employers.
"We're shocked to hear the national media coverage today," he said. "The Litchurch Lane factory site is a unique asset for Derby and we understand the impact these job losses will have on our residents and the wider region.
"As a council, we're ready to play our part and urge the government and unions to work closely with Alstom to ensure a sustainable future for the factory, which would not only benefit the thousands of staff at the site, but many more across the local supply chain.
"The rail sector is immensely important to the city, and was recognised earlier this year with Derby being named the home for the new Great British Railways headquarters. We stand with Alstom and their workers during this challenging time and pledge to support wherever we can."
Steve Turner, assistant general secretary for manufacturing at the Unite trade union, told the Times newspaper the lack of work for the factory "could be devastating for Derby and we could be looking at the destruction of the rail supply chain in general in this country".
A spokesperson from Alstom UK and Ireland emphasised no decision had been taken.
They said: "Derby is very important to Alstom and to the UK rail sector.
"It is the only UK factory that can design, engineer, build and test trains for domestic and export markets.
"We are committed to working with government to secure a sustainable future for the factory, our 2,000 staff and the over 1,400 UK suppliers we work with."
A Department for Transport spokesperson said: "Rail manufacturing plays an important role in growing the UK economy and delivering better services for passengers.
"The government remains committed to supporting the entire sector."We remain in contact with Alstom as it develops a sustainable future for its Derby site."
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