Leaders at Sheffield Council have called on the Government to protect thousands of workers employed locally at Liberty Steel amid a closure threat.
Liberty Steel's Stocksbridge site is a key part of the city's economy and employs around 2,000 people in Sheffield and Rotherham.
But it is facing an uncertain future after HMRC last week issued winding up orders against the company.
Read more: go here for more Yorkshire and Humber business news
The tax authority has made an application to a court to wind up the company over unpaid debts believed to be £25 million.
Coun Julie Grocutt, who represents the Stocksbridge and Upper Don ward, said: "This is a devastating time for all the people who work at the steelworks, for their families and indeed for the whole town.
"The steelworks is such an important part of our town we really need to secure its future. We have called for the Government to protect this site before, and we really need that support more than ever to protect this hugely important local asset."
Unions GMB, Unite and Community said Liberty Steel is a strategically important business, crucial to delivering net zero, and "under no circumstances can our plants be allowed to close".
Most Read
The steelworks has been part of the town's history since the 1840s and is the home of the paragon umbrella frame. Its highly specialised products supply the aerospace industry as well as oil and gas.
The news came as Sheffield Council leader Terry Fox visited Stocksbridge to discuss local issues as well as the £24.1m Town's Fund investment.