NATO Secretary-General Jens Stoltenberg said: "Our aim remains to support the Afghan government and security forces as much as possible. The security of our personnel is paramount."

He added that NATO continues to assess the developments on the ground, and ''we are in constant contact with the Afghan authorities and the rest of the international community''.

NATO has also raised concerns over the rapid increase of Taliban violence in the country.

"NATO Allies are deeply concerned about the high levels of violence caused by the Taliban’s offensive, including attacks on civilians, targeted killings, and reports of other serious human rights abuses," Stoltenberg noted.

NATO stressed that the Taliban will not get international legitimacy if the militants gain power through a military takeover.

"Taliban need to understand that they will not be recognized by the international community if they take the country by force," Stoltenberg added.

"We remain committed to supporting a political solution to the conflict," he said.

Further Reading: Undeserved legitimacy given to Taliban in peace talks: Afghan govt

This comes after the Taliban captured as many as 18 provincial capitals.

Meanwhile, Afghanistan’s First Vice President Amrullah Saleh on Friday said the government will continue its fight against the Taliban by fully supporting the Afghan National Defense and Security Forces and the public uprising forces.

Saleh said it was a key decision made by the government’s security meeting chaired by President Ghani.

"In today’s meeting on national security chaired by President Ashraf Ghani, it was decided with conviction and resolve that we stand firm against Taliban terrorists and do everything to strengthen the national resistance by all means and ways," Saleh said in a tweet.

In another post, Saleh said that the Taliban will be defeated and that he will never surrender to the group.

He did not provide details on the reasons behind the current situation in the country but said he will not bow to any deal named peace with the nature of surrender.

"I will never accept Taliban domination on the people of Afghanistan under any deal that is dictated and imposed by Taliban," Saleh added.

The Taliban have toppled six provincial capitals in the past 24 hours taking the number of provinces fallen to the Islamist militia to 18.

The centres of Kandahar, Helmand, Herat, Badghis, Ghor, Logar, Zabul, and Oruzgan provinces fell to the Taliban in the past 24 hours.

In addition, in other provinces like Paktia and Wardak, the Afghan government forces only control the provincial capitals while the Taliban are controlling the rest of the geography.

In Herat  province, former warlord Ismail Khan, deputy interior minister Abdurahman Rahman, Governor Abdulsabor Qani, commander of Afghan National Army Zafar corps and head of National Directorate of Security local office surrendered to the Taliban.