Anil Ambani Group company Reliance Communications, which is in the process of bidding for Hutch-Essar, is planning to list its undersea cable business unit Flag Telecom in London to raise over $500 million.The company plans to dilute 20-24% stake in the company through the listing on LSE, sources said.When contacted, an RCL spokesperson declined to comment. Sources said the process of preparation for the listing would start next month.Flag Telecom provides network infrastructure and data services to telecom operators and content providers across the world.Anil Ambani last month unveiled a $1.5 billion investment in Flag, designed to increase its network by 43% to 115,000 km and add extra capacity for voice calls, internet and multimedia services amid rising global demand.The expansion will extend India's largest internet protocol network to destinations in south-east Asia, Africa, the Mediterranean and the Pacific, including links between Japan, China and the US west coast.The fibre-optic cable would eventually reach 60 countries and connect 5 billion global customers.