Feb 15 Nippon Steel & Sumitomo Metal Corp would be willing to participate in a capital increase for ailing Brazilian steelmaker Usinas Siderurgicas de Minas Gerais SA if an understanding with other shareholders were reached in principle, a source with direct knowledge of the matter said on Monday. The source, who spoke under condition of anonymity due to the sensitivity of the issue, said that an accord between Nippon Steel and Techint Group - the other controlling shareholder of the steelmaker known as Usiminas - for a capital injection may not happen before Usiminas releases fourth-quarter results on Thursday.