Tata Steel is believed to be selling its UK assets, including Port Talbot, sources told the Press Association.
The development casts doubt over the future of thousands of steelworkers' jobs across the UK.
Union leaders travelled to Mumbai where the Tata board met to discuss the company's loss-making UK business.
They had been hoping Tata would agree to a turnaround plan to keep steelmaking in Port Talbot and other UK plants.
The news will affect other Tata plants including Rotherham, Corby and Shotton.
Tata announced over 1,000 job cuts in January, with 750 in Port Talbot.
Thousands of steel jobs have been lost in the past year, with companies blaming cheap Chinese imports and high energy costs