Nippon Steel Corp., JFE Holdings Inc. and Posco, Asia's three largest steelmakers, will join Cia. Vale do Rio Doce to increase production almost fourfold at a jointly owned coal mine in Australia.

The companies will invest A$400 million ($379 million) at the Carborough Downs mine in Queensland state to increase output to 3.7 million tons from 1 million tons by July 2009, JFE said today at a press briefing in Tokyo. Vale, based in Rio de Janeiro, is the world's biggest iron-ore producer.

Vale, which operates the mine and owns 80 percent of it, is expanding output to meet growing demand for the steelmaking material in China and Japan.

Floods disrupted mining this year in Australia, the world's largest exporter of coking coal, forcing at least six producers to warn of delayed shipments.

Steelmakers have had to cut output because of the shortage, according to Macquarie Bank Ltd.

Plans for increasing steel production and supply cuts have pushed coking coal prices to record highs this year, with Nippon Steel, the world's second-biggest maker of the metal, agreeing to pay $300 a ton for the material for the year from April 1, more than triple the previous year's long-term contract rate.

JFE Shoji Holdings Inc., JFE's trading unit, and Tata Steel Ltd., India's biggest maker of the alloy, are also participating in the expansions.