(Adds Usiminas securities filing, stock suspension by Brazilian stock exchange)
By Tatiana Bautzer
SAO PAULO, Aug 23 (Reuters) - Brazilian steelmaker Usinas Siderurgicas de Minas Gerais, known as Usiminas, has hired Banco BTG Pactual SA to sell its 70 percent stake in its mining company, one person with knowledge of the matter said on Thursday.
Trading on Usiminas stock was suspended for around 40 minutes by Brazilian stock exchange B3 SA Brasil Bolsa Balcão after reports of the potential sale.
Preferential shares, the most liquid class of Usiminas stock, were down 1.1 percent before trading was halted and expanded losses to 1.4 percent, at 7.98 reais, when trading resumed a few minutes before the market closed.
In a securities filing, Usiminas said it hired Banco BTG Pactual to "consider alternatives" for its 70 percent stake in Musa but had not made any sale decision.
Usiminas declined to comment further.
Brazilian newspaper Valor Economico reported earlier on Thursday, citing sources, that Mineração Usiminas, known as Musa, could be valued at 1 billion reais ($255.6 million) and that Japan's Sumitomo Corp, which already has a 30 percent stake in Musa, could acquire more of the company.
The person interviewed by Reuters said the process is in its early stages and did not confirm the valuation nor the potential buyer that Valor reported. ($1 = 3.9122 reais) (Reporting by Tatiana Bautzer Additional reporting by Paula Laier Editing by Chizu Nomiyama and Lisa Shumaker)