BEIJING - China's Ministry of Land and Resources announced Tuesday that authorities in the country have found and ordered the clean-up of more than 280 illegal mines in an effort to regulate the exploration of valuable minerals, such as rare earths.

The number of explorations for minerals such as rare earth, tungsten, tin, and antimony were reduced to 116 from 400 in 11 provinces and regions in the country in spot checks led by teams dispatched by the ministry, a statement on its website said.

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The campaign, initiated last June by the ministry, has aimed to end the illegal and sometimes widespread excavation of valuable minerals.

The ministry earlier ordered that the clean-up of illegal mines should be completed before the end of November.

China supplies 90 percent of the world's rare earth minerals, even though it has only around 36 percent of the world's reserves.

The Chinese government has also increasingly focused on the environmental impact from rare earth explorations, as its rare earth export quotas stood at 30,300 tons for 2010, a drop of almost 40 percent from 2009.