SINGAPORE/LISBON, Oct 26 (Reuters) - Energias de Portugal is in advanced talks to acquire a majority stake in Sunseap Group in a deal that will value the Southeast Asian renewables firm at around S$1 billion ($742 million), three sources with knowledge of the matter said on Tuesday. EDP Renovaveis (EDPR), 75% owned by Portugal’s biggest utility, is in late-stage negotiations to buy out the stake held in Sunseap by Thai energy firm Banpu PCL, Singapore state investor Temasek Holdings, a Temasek-backed fund and other investors, the sources said. The sources declined to be identified due to confidentiality constraints. EDP, Banpu, Sunseap and Temasek all declined to comment. Banpu holds a nearly 49% stake in Sunseap through a subsidiary, which it has built up since its initial investment in the group in 2017. Details of stakes held by other shareholders have not been made public. Sunseap also counts Japanese firms and other companies among its investors. Two of the sources said EDPR is seeking to own a significant majority in Sunseap and is also considering investing at least $1 billion in the firm’s business over the next few years. EDPR’s move to snap up the Singapore-based solar energy group reflects the world’s fourth largest renewable energy producer’s ambition to accelerate its growth in Asia. $1 = 1.3483 Singapore dollars Reporting by Anshuman Daga and Roslan Khasawneh in Singapore and Sergio Goncalves in Lisbon; Editing by Jan Harvey