From January to November 2010, China's rare earths exports totaled 35,000 tons, the Commerce Ministry said Tuesday without explaining how the annual government-approved quota of 30,300 tons had been exceeded.

It said the value of exports soared 171 percent over 2009 due to higher prices.

More than 80 percent of exports last year went to Japan, Europe and the United States, said ministry spokesman Yao Jian.

China accounts for most rare earths mining and manufacturers that need them to produce mobile phones computer drives and hybrid cars were concerned when Beijing announced in 2008 it would begin to reduce annual export quotas.

"China will continue to oversee the production of rare earths and will export rare earths globally according to trade regulations," Yao said at a news briefing.

The United States, Canada and Australia have rare earths but stopped mining them in the 1990s as lower-cost Chinese supplies became available. China has about 30 percent of rare earths deposits but accounts for about 97 percent of production.

Countries were alarmed when Beijing blocked shipments of the minerals to Japan last year after a Chinese fishing boat captain was detained near disputed islands.

China says it wants to conserve dwindling resources and reduce environmental damage due to mining. But some commentators have suggested Beijing is trying to support growth of its own manufacturers of lightweight magnets and other products made of rare earths by reducing supplies available to foreign competitors.