The Taliban has said it sees China as a "friend" of Afghanistan and assured Beijing that it would not host Uyghur Islamic militants from the volatile Xinjiang province, which is a major worry for the Chinese government, according to a media report.

The comments came as the Taliban made territorial gains in the war-torn country amid the withdrawal of the US forces. China has already evacuated 210 of its nationals from Afghanistan by a chartered flight this week.

Beijing is concerned that under Taliban rule, Afghanistan will become a hub for the East Turkistan Islamic Movement (ETIM), a separatist outfit aligned to Al-Qaeda which is waging an insurgency in Xinjiang.

The resource-rich Xinjiang shares about 8- km-long border with Afghanistan.

Playing down China's concerns, the Taliban spokesman Suhail Shaheen said they see China as a friend to Afghanistan and is hoping to talk to Beijing about investing in reconstruction work as soon as possible.

Suhail also said the Taliban would no longer allow China's Uyghur separatist fighters from Xinjiang, some of whom had previously sought refuge in Afghanistan, to enter the country.

The Taliban would also prevent al-Qaeda or any other terrorist group from operating there, he said.

We have been to China many times and we have good relations with them, Suhail told Hong Kong-based South China Morning Post, recalling the few meetings hosted by China in the past for Taliban delegations.

China is a friendly country and we welcome it for reconstruction and developing Afghanistan, he said adding that "If (the Chinese) have investments, of course, we will ensure their safety," Shaheen said.

Sharply critical of the US move to pull out its troops without stabilising the peace process in Afghanistan, China this week has asked its close ally Pakistan to step up cooperation to contain the security risks in the war-torn country following the withdrawal of the foreign forces.

"(China and Pakistan) need to defend regional peace together. Problems in Afghanistan are practical challenges that China and Pakistan both face," especially the expansion of both international and regional terrorism, Chinese Foreign Minister Wang Yi said on Tuesday addressing a meeting of the 70th anniversary of diplomatic relations with Pakistan.

While the American troops' withdrawal and resurgence of the Taliban should strategically benefit China as the Taliban shares close ties with Pakistan, both Islamabad and Beijing are concerned as they faced threats from the Islamic militant groups which were part of Al-Qaeda and Taliban.

China has been eying big scale investments in Afghanistan as the country has the world's largest unexploited reserves of copper, coal, iron, gas, cobalt, mercury, gold, lithium and thorium, valued at over USD one trillion.

In 2011, the China National Petroleum Corporation (CNPC) won a USD 400 million bid to drill three oil fields for 25 years, containing roughly 87 million barrels of oil.

Chinese firms have also gained rights to mine copper at Mes Aynak in Logar province, according to the Post report.

But observers say China will remain very cautious and concerned about the Taliban delivering on its promises.

Whatever benign language the Taliban use, China remains highly concerned about the security situation there, Andrew Small, a senior transatlantic fellow with the German Marshall Fund's Asia Programme told the Post.

He said China's biggest concern in its dealings with the Taliban had always been whether it was sheltering Uyghur separatists.

China's crackdown in Xinjiang, observers say, has exasperated the resentment among native Uyghur Muslims in Xinjiang. The US, the EU and international human rights organisations have accused Beijing of committing genocide in the province.

The 12th report of the Analytical Support and Sanctions Monitoring Team of the UN last month confirmed the presence of ETIM militants in Afghanistan.

The Eastern Turkistan Islamic Movement (ETIM) consists of several hundred members, located primarily in Badakhshan and neighbouring Afghan provinces," the report submitted to the UN Security Council said.

The report said that large numbers of Al-Qaeda fighters and other foreign extremist elements aligned with the Taliban are located in various parts of Afghanistan.