Rio Tinto's coal assets in Australia are being eyed by suitors from China and India.

Sam Walsh, Rio Tinto's new chief executive, placed the company's assets on the sale market to raise funds that will help it slash some $26 billion in debt as well as protect its single-A credit rating.

The sale includes a 29 per cent stake in its Coal & Allied business and majority stake in the Clermont mine in Queensland state. Analysts said the Coal & Allied stake could fetch around $1.7 billion, while the Clermont stake could bring in $1.5 billion.

Among the companies found to be mulling to place bids for the Australian coal assets include India's Aditya Birla Group and China's state-owned Shenhua Group Corp Ltd, according to a Reuters report.

Although Japanese trading house Mitsubishi Corp has pre-emptive rights to buy the stakes, it had earlier said it is not currently planning to expand its portfolio of natural resource investments. Mitsubishi Corp controls 20 per cent of Coal & Allied. It is also a co-owner in the Clermont mine, along with Japan's Electric Power Development Co Ltd and a consortium of other Japanese utilities.

China and India are expected to continue to propel the demand for coal with its growing population and rising economic powers.

Global trade in metallurgical coal, according to Australia's Bureau of Resources and Energy Economics (BREE), will increase at an average annual rate of five per cent, from 271 million tonnes in 2011 to 345 million tonnes in 2017. India, China as well as Brazil will push this, spurred by robust growth in steel production.

As of 2011, the top global coal importers included China, Japan, South Korea, India, Taipei, Germany, and UK, according to the World Coal Association.