AIA Group Ltd. and Manulife Financial Corp. are among bidders for Siam Commercial Bank Pcl’s life insurance operations in what could be the biggest-ever acquisition of a Southeast Asian insurer, people with knowledge of the matter said. Thai billionaire Charoen Sirivadhanabhakdi is partnering with Singapore’s Great Eastern Holdings Ltd. on a non-binding offer, while Hong Kong tycoon Richard Li’s FWD Group and, separately, Prudential Plc have also bid, according to the people.