The Siam Commercial Bank Public Company Limited (SET:SCB) has begun to formally seek bids for its life insurance business in a sale that could raise about $3 billion, said people with knowledge of the process. Prudential plc (LSE:PRU), AIA Group Limited (SEHK:1299) and Manulife Financial Corporation (TSX:MFC) are among insurers weighing a bid for SCB Life Assurance, the people said.