China made progress in strengthening its new spot iron ore trading platform by signing up the mining giant Rio Tinto, Australia's largest iron ore producer, as one of its members.

Rio Tinto's participation marks a victory for the China Beijing International Mining Exchange (CBMX), which is trying to broaden its market participation. The electronic trading platform, which will officially start operation in May, is designed to strengthen China's pricing power on iron ore.

The move came a day after Brazilian miner Vale signed a memorandum of understanding with CBMX to support the development of the platform, though Vale is yet to officially join the network.

The CBMX is widely seen as a rival to the Singapore-based globalORE trading exchange backed by Australia's second largest iron ore producer BHP Billiton.