Brazilian steel group CSN is reported to be preparing to trump India's Tata Steel and make a rival takeover bid for Anglo-Dutch firm Corus.
Corus employs 24,000 people in the UK
CSN has appointed investment bank Lazards to advise it on launching a counter offer, said the Sunday Times.
Meanwhile, German steel group Thyssenkrupp denied it was interested in beating Tata's £4.3bn ($8.1bn) bid.
Tata's offer was formally accepted by the Corus board on Friday morning but still needs Corus shareholder backing.
CSN describes itself as one of the largest steel firms in Latin America, employing 8,000 people.
It has overseas operations in the US and Portugal.
Corus employs 47,300 people worldwide, including 24,000 in the UK at plants at Port Talbot, Scunthorpe and Rotherham.
It was formed out of the 1999 merger of British Steel and Dutch group Hoogovens.
A combined Tata Steel and Corus group would create the world's fifth largest steel business.
Tata has said it could not rule out any job cuts at Corus if its takeover is successful.