LHASA, July 23 (Xinhua) -- Tibet is planning to levy a deposit on mining companies that wish to exploit its mineral resources, an effort designed to regulate mining practices and minimize their impact on the fragile ecosystem, the local authorities said on Monday.

By the end of this year, all mining companies operating in Tibet will have to pay a deposit, an amount that would not be refundable if their mining activities were to damage the local environment, said Wang Baosheng, an official in charge of land and resources in the southwestern Chinese autonomous region.

Wang said the damage would be evaluated by the local environmental watchdog. If there is severe damage to the vegetation, rivers and wetlands, the deposit money will be used to remedy the situation.

He refused to reveal how much the deposit a company would have to pay. Relevant regulations are being made and the general principle is to give equal emphasis on environment protection and economic development, he said.

Zhongkai Mining Co. Ltd, based in Lhasa, predicts environment spending will make up 30 percent of its total mining operation costs. The threshold is pretty high for small companies, said the company's deputy general manager Zhang Jiaquan. Tibet has 101 known minerals, including chromium, copper, iron and boron.

The regional government has decided to ban the mining of gold, mercury, arsenic and peat to preserve the mineral resources and protect the environment.

Tibet is rich in all these resources but has to consider the environmental costs behind excessive mining, said Wang. Mercury and arsenic mining pollutes water supplies, peat mining can destroy wetlands and gold mining can ruin grasslands and rivers. The local investment bureau said mining had become one of the pillar industries in Lhasa after the Qinghai-Tibet Railway opened in July 2006. Both could be detrimental to the environment, said Zhang Bifang, vice director of Lhasa Investment Bureau. She said the new regulations would expose mining companies to higher risks and only companies that fulfil their environment protection liabilities would remain in the market.

Dubbed as Asia's Water Tower, the Qinghai-Tibet Plateau has abundant resources of water, wetlands and grasslands. Thirty-eight nature reserves have been established in Tibet encompassing an area of 408,300 square kilometers, accounting for 34 percent of the region's total land area.