China is ready to deepen "friendly and cooperative" relations with Afghanistan, a government spokeswoman said Monday, after the Taliban seized control of the country. 

Beijing has sought to maintain unofficial ties with the Taliban throughout the US' withdrawal from Afghanistan, which spurred an advance by the Islamist hardliners across the country that saw them capture the capital Kabul on Sunday.

China shares a rugged 76-kilometre (47-mile) border with Afghanistan.

Beijing has long feared Afghanistan could become a staging point for minority Uyghur separatists in the sensitive border region of Xinjiang.

But a top-level Taliban delegation met with Chinese Foreign Minister Wang Yi in Tianjin last month, promising that Afghanistan would not be used as a base for militants.

In exchange, China offered economic support and investment for Afghanistan's reconstruction.  

On Monday, China said it "welcomed" the chance to deepen ties with Afghanistan, a country that has for generations been coveted for its geo-strategic importance by bigger powers.

"The Taliban have repeatedly expressed their hope to develop good relations with China, and that they look forward to China's participation in the reconstruction and development of Afghanistan," foreign ministry spokeswoman Hua Chunying told reporters. 

"We welcome this. China respects the right of the Afghan people to independently determine their own destiny and is willing to continue to develop... friendly and cooperative relations with Afghanistan." 

Hua called on the Taliban to "ensure a smooth transition" of power and keep its promises to negotiate the establishment of an "open and inclusive Islamic government" and ensure the safety of Afghans and foreign citizens.

China's embassy in Kabul remains operational, Hua said, although Beijing began evacuating Chinese citizens from the country months ago amid the deteriorating security situation. 

In a statement Monday, the embassy told Chinese citizens remaining in Afghanistan to "pay close attention to the security situation" and stay indoors.

US President Joe Biden promised a complete withdrawal of US troops by September 11, marking an end to two decades of war. 

But Washington was left shocked by the rapid collapse of the Afghan government and the Taliban's sweeping advance.

China has repeatedly criticised what it sees as the US' hasty withdrawal from Afghanistan as a failure of leadership. 

Stability and business 

The Taliban's takeover opens a strategic door to China laden with both risk and opportunity. 

Maintaining stability after decades of war in its western neighbour will be Beijing's main consideration, as it seeks to secure its borders and strategic infrastructure investments in neighbouring Pakistan, home to the China-Pakistan Economic Corridor. 

For Beijing, a stable and cooperative administration in Kabul would pave the way for an expansion of its Belt and Road Initiative into Afghanistan and through the Central Asian republics, analysts say.

The Taliban meanwhile may consider China a crucial source of investment and economic support, either directly or via Pakistan -– the insurgents' chief regional patron and a close Beijing ally. 

China has so far stopped short of officially recognising the Taliban as the new leaders of Afghanistan, but Wang Yi called them a "decisive military and political force" during last month's meeting in Tianjin.