British Steel is pausing production at one of its plants on Teesside for at least three weeks.
The Tees Valley Mayor said he had been assured by the company there would be no job losses with staff expected to be furloughed.
British Steel CEO Ron Deelen said the move at Skinningrove was due to a fall in demand amid the coronavirus outbreak.
Sites at Lackenby and Darlington are not affected.
Operations at the firm’s service centre in Lisburn, Northern Ireland are also being reduced “for a short time”.
“As we manage the internal and external challenges coronavirus brings, we’ll take decisive action to protect our people and our operations,” Mr Deelen said.
“These are both temporary measures in the face of difficult market conditions, and we’ll provide all the support our employees deserve and require.”
The firm said it was following government guidance in its manufacturing operations and hundreds of office-based employees were now working from home.
Tees Valley Mayor Ben Houchen said the decision “will come as no surprise”.
“I have spoken to British Steel and I have been reassured that there will be no job losses at all as a result of this,” he said.
“It is expected that all staff will be furloughed.”