China has begun looking at funding a railway and port that would service Rio Tinto's Simandou iron project in Guinea and cost more than US$10 billion, said four people with direct knowledge of the matter. The agency overseeing companies owned by the Chinese government had gauged interest from state rail and port builders and contacted China Development Bank about providing financing, said the people, who asked not to be identified as they were not authorised to speak publicly about the matter. Guinea's inability to fund the rail line from its coast to Simandou, described by Rio as the world's largest untapped deposit of iron ore, had "effectively frozen" the project, former mines minister Mahmoud Thiam said in April. State-owned Aluminum Corp of China paid US$1.35 billion for a 44.65 per cent stake in the project in 2010. The Guinea government currently has an obligation to finance 51 per cent of the 650-kilometre railway and port, which President Alpha Conde said in June that the country was willing to pass to another party. Rio chief executive Sam Walsh said last week that the miner reached an agreement with Guinea that would allow a third party to fully fund the transport links. China's State-owned Assets Supervision and Administration Commission was speaking to companies about the project, the people said, adding that it was not clear which firms had expressed interest. Alkhaly Yamoussa Bangoura, mines adviser to Guinea's president, said on Monday that China was involved in the project.