Nippon Steel & Sumitomo Metal Corp is seeking a negotiated end to a dispute with a partner over their interests in Usinas SiderAorgicas de Minas Gerais SA, the latest chapter in a rift over control of Brazil's largest listed flat steelmaker. Nippon Steel, which along with Italo-Argentine industrial conglomerate Techint Group share control of the Brazilian mill known as Usiminas, requested that Brazil securities industry watchdog CVM investigate actions by Techint and its subsidiary Ternium SA in the company, according to a securities filing.