Liberty Steel is set to cut about 350 jobs across its South Yorkshire and South Wales operations in response to "challenging market conditions and a lingering reduction in demand".
The group has taken the decision to reduce its workforce at certain plants to match sustainable production forecasts.
The move follows a review of its UK business in response to "challenging market conditions and a lingering reduction in demand for UK steel products".
Its workforce is set to be reduced by up to 355, with sites in Stocksbridge, Rotherham, Brinsworth and Newport affected.
In response to the job cuts the national officer of the GMB union, Ross Murdoch, said: "Once again we have more bad news for the UK steel industry.
“A country that doesn't produce its own steel for key infrastructure projects and shipbuilding is a country that's destined to fail.
"Our steelworkers deserve better than this.
"The Government urgently needs to intervene and ensure steel companies in the UK receive the backing they have long called for on energy costs and business rates.”
Huddersfield sex offender jailed after abusing teenage boy
Two men sentenced after robbery in Manchester city centre
Plans for new Leeds Kirkgate Market attraction move forward
Big Doggie Do set to return to Milton Keynes
Bradford Council appoints David Watson as new culture and events director
Culture at the Heart of Stockport’s Transformation
South Asian Art Exhibition Opens at Cartwright Hall
Men’s Mental Fitness Programme Launches in Blackburn
Former Teacher Charged with 1990s Child Sex Offences
Council Calls for Tougher Fly-Tipping Sentences
Man Jailed for Raping and Exploiting Vulnerable Teen in Stockport
Free Midsummer Festival to Return to Milton Keynes
The Golden Era
Alim OnAir
Bhangra Nights
Legal Show