By Michael Martina
BEIJING (Reuters) - China does not seek to fill a void left in Afghanistan by the withdrawal of U.S. troops but will play a "huge" commercial role in helping rebuild the country, a newly appointed Chinese special envoy said on Monday.
China, which is connected to Afghanistan by a narrow, almost impassable mountain corridor, has been quietly preparing for more responsibility there after the bulk of U.S.-led troops pull out by the end of this year.
Some Western officials have said China is likely to emerge as a strategic player in Afghanistan but Sun Yuxi, who was appointed special representative to the country on Friday, said China's involvement would remain largely commercial.
"This idea about filling a void after the withdrawal of troops, I think it doesn't exist," Sun told reporters in Beijing before heading to Afghanistan on Tuesday for talks.
Some Western officials have criticized China for piggy-backing off the U.S.-led security operation that has eliminated an al Qaeda enclave on China's door-step and opened up Afghanistan's resources to international exploitation.
China's commitment to Afghan reconstruction since the ouster of a hardline Islamist regime in 2001 has been a relatively paltry $250 million and its security support has been mostly limited to counter-narcotics training.
But a consortium of Chinese investors is involved in a landmark $3 billion deal to produce copper in Afghanistan although work on the deposit, among the world's largest, has been largely halted by insurgent attacks.
Sun said China looked forward to much more economic involvement which he said was essential for stability.
"In the long-term, an even greater portion of our cooperation and participation in economic rebuilding will be carried out in a commercial way. This amount will be huge," he said.
"Preserving Afghanistan's stability is not a matter of adding troops but of helping Afghanistan to quickly rebuild. We hope to see a rapid decrease in weaponry and a rapid increase in wealth."
Sun, a veteran diplomat with experience of Afghanistan since the late 1970s, said U.S.-China cooperation on Afghanistan had been one of the "very bright highlights" in ties between the powers, whose relations are often testy.
He welcomed the withdrawal of the bulk of U.S.-led troops and also welcomed the expected maintenance of a small, residual U.S. force.
"The new Afghan government should mainly be responsible for security. The United States is preparing to withdraw, and we welcome that," he said.
"We also welcome the United States retaining some military bases to observe for a time and cooperate to help the Afghan people and government fight terrorism."
A major worry for China is that ethnic Uighur separatist militants from its western Xinjiang region will take advantage if Afghanistan again descends into chaos.
Uighur fighters are believed to be based in militant strongholds in ungoverned stretches of the Afghan-Pakistani border.
Sun said he did not know how many were there but there had been hundreds before the U.S. invasion of Afghanistan to oust the Taliban in 2001.
"At the peak, there was about 1,000 people training there," Sun said, adding that many were killed or captured in fighting but most had fled.
China says Islamist militants were behind a spate of recent attacks there in which about 200 people have been killed.
Exiled Uighur groups and human rights activists say repressive government policies in Xinjiang, including controls on Islam and on Uighur culture, have provoked unrest. China dismisses that.
(Editing by Robert Birsel)