China on Tuesday said the withdrawal of US troops from Afghanistan after a 20-year conflict signalled the country has "turned a new page", after Beijing criticised Washington's chaotic exit.

China has repeatedly slammed what it sees as a hasty and ill-planned US withdrawal and has said it is ready to deepen "friendly and cooperative" relations with the Taliban following their takeover.

The United States completed its military retreat from Afghanistan on Monday, ending its longest war to cries of shame at home and celebratory gunfire in Kabul from the Taliban.

"Afghanistan has been able to free itself of foreign military occupation," Chinese foreign ministry spokesman Wang Wenbin said at a regular briefing. 

"The Afghan people have ushered in a new beginning for national peace and reconstruction, and Afghanistan has turned a new page." 

China's embassy in Kabul remains operational, although Beijing began evacuating Chinese citizens from the country months ago as security deteriorated.

But Beijing has not yet recognised the Taliban as the de facto government, and is wary of the militant group providing support to Muslim-minority Uyghur separatists looking to infiltrate its sensitive border region of Xinjiang.

"We hope that Afghanistan will form an open, inclusive and broadly representative government... and resolutely crack down on all kinds of terrorist forces," Wang said.

A top-level Taliban delegation met with Chinese Foreign Minister Wang Yi in Tianjin last month and promised Afghanistan would not be used as a base for militants.

For Beijing, a stable and cooperative administration in Kabul would pave the way for an expansion of its overseas infrastructure drive, analysts say.

The Taliban meanwhile may consider China a crucial source of investment and economic support.

Chinese companies have also been eyeing Afghanistan's vast copper and lithium mines but experts say the perilous security situation means any immediate commodities rush by investors is unlikely.