Ninety-five percent of the global supply of the 17 metals vital in technologies like electronics and computers are produced in China, which has set restrictive export quotas.
The United States, Europe and Japan have lodged a formal complaint with the World Trade Organization against China's export restriction, NewScientist.com reported.
However, China's quotas may have helped push up demand and prices, making extraction a more cost-effective proposition, with the result that mining of rare earths in countries other than China has begun.
In 2010, U.S.-based Molycorp reopened the Mountain Pass mine in California for the first time in eight years while Australia's Alkane Resources has a pilot plant in New South Wales with plans to start large-scale mining by the end of 2013.
Resumption of mining outside China could have benefits, one researcher says, because rare earths are often mixed with radioactive uranium and thorium which must be carefully disposed of, and the processing of ores involves toxic acids.
"It would be very good for mining to take place in countries where regulations are strict and can be enforced," said David Manning of Newcastle University in England.
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