Australia's hyperactive coal mining sector offered up the prospect of another deal Monday when Whitehaven Coal Ltd. and Aston Resources Ltd. said they were in merger talks that could lead to the creation of a A$4.76 billion ($4.88 billion) coal producer.

Both companies said the talks were based on a merger of equals, despite a large disparity in the values of the would-be partners. Whitehaven had a market capitalization of A$2.82 billion at the close of trading Monday, 45% higher that Aston Resources' A$1.94 billion valuation.

Analysts were skeptical that Whitehaven would be able to sell a merger to shareholders on the basis of a 50-50 split. "Whitehaven's marketable reserves at 426 million metric tons are a third larger than Aston's 329 million tons, and its resources of 1.78 billion tons are more than double Aston's 679 million tons," IG Markets Ltd. analyst Stan Shamu noted Monday. "Whitehaven may have had its problems, but it still produced 4.7 million tons last year, and Aston is yet to mine anything."

Aston, which is about 30% owned by its chairman, Nathan Tinkler, has a 75% stake in the Maules Creek project in the Australian state of New South Wales. Brisbane-headquartered Aston paid A$480 million in 2010 to buy the operation from Rio Tinto Group and in October agreed to sell a 10% holding in the operation to Japan's Electric Power Development Co. Ltd. for A$370 million. Based on that valuation its stake in Maules Creek would be worth about A$2.78 billion, bringing its overall valuation closer to that of Whitehaven. Japan's Itochu Corp. owns the other 15% of the Maules Creek project.

Maules Creek is scheduled to begin production in the second quarter of 2013 and is expected to produce about 12 million tons of semi-soft coking coal and high-grade thermal coal, both for export, by 2014. The project is located about 10 miles from Whitehaven's Narrabri North Mine. Whitehaven, which operates four mines, all located in the same basin as Aston's Maules Creek project, is planning to increase production to about 15 million tons per year. News of the discussions comes just over seven months after Sydney-based Whitehaven abandoned efforts to sell itself, declaring that bidders from India, China and the U.S. failed to meet its expectations.

Whitehaven said Monday that it was still pursuing a range of potential deal options. "It is unclear at this stage as to whether the terms of any such potential transaction would be suitable to put to Whitehaven shareholders," Whitehaven managing director Tony Haggarty said in a statement.

The coal sector has been one of Australia's most active deal arenas for the past three years as both mining companies and end users snap up assets to secure supplies in the expectation of continued strong demand from China and India. There have been more than 70 Australian coal sector deals so far this year, totaling more than A$9 billion, including Peabody Energy Corp.'s A$4.9 billion acquisition of Macarthur Coal Ltd.

Whitehaven shares closed Monday at A$5.71, up A$0.07, or 1.2%. Aston Resources closed at A$9.49, up A$0.38, or 4.2%.