China's Yanzhou Coal Mining Co and India's Aditya Birla group are among parties preparing to submit second-round bids for Australian coal miner Whitehaven Coal which is seeking offers of more than $3.5 billion, sources said on Tuesday.

Coal miner Peabody Energy Corp was also still looking at Whitehaven, although it was unclear whether it would submit a binding offer, one of the sources familiar with the transaction told Reuters.

Whitehaven said in February it had selected a short list of bidders to complete due diligence in a process expected to continue for "a number of months."

Second round bids for Whitehaven were expected within weeks with about three to four interested parties in the mix, a second source said.

India's Birla was looking at bidding for Whitehaven alone, one of the sources told Reuters, although there had been efforts to encourage a number of Indian firms to bid as a consortium. One of the sources denied media reports that India's Gujarat NRE Coke was also looking.

Whitehaven did not respond to requests for a comment.

Korea Resources Corp said on March 9 that its consortium had pulled out of bidding for Whitehaven.

China's Shenhua Group and China Coal had also taken a look at Whitehaven but Chinese bidders had now been narrowed down to one, one of the sources told Reuters.

Birla, a telecoms-to-cement conglomerate, has thermal coal requirements for group companies Hindalco, India's top aluminium producer, and UltraTech Cement, the country's largest cement producer.

A Birla spokeswoman in Mumbai declined to comment, while Yanzhou was not immediately available to comment.

Large Whitehaven shareholder Alpha Natural Resources was not expected to bid after agreeing in January on a $7.1 billion deal to buy Massey Energy Co.

Sources familiar with the deal have said previously that Whitehaven was seeking bids of at least A$7.50 per share which would value the target at around A$3.7 billion. Whitehaven shares closed 1.1% lower at A$6.61 on Tuesday.

The sources could not be named since they were not authorized to speak to the media about the matter.