United Nations Secretary-General Antonio Guterres is following the ongoing situation in Kabul, especially at the airport, with great concern, his spokesman Stephane Dujarric said at a noon briefing on Thursday.

"He condemns this terrorist attack which killed and injured a number of civilians, and extends his deep condolences to the families of those killed. He stands in solidarity and wishes a speedy recovery to those injured," said Dujarric.

"This incident underscores the volatility of the situation on the ground in Afghanistan but also strengthens our resolve as we continue to deliver urgent assistance across the country in support of the Afghan people," the spokesman added.

At least 73 people were killed after twin attacks in Kabul on Thursday.

Guterres also sent letters formally inviting the United States, Britain, France, Russia and China to meet on Monday to discuss the chaotic situation in Afghanistan.

The full UN Security Council last met on Afghanistan on August 16, a day after the Taliban took over Kabul, capital city of the war-torn country.

Monday's discussion comes as Britain and France work on a UN resolution on Afghanistan.

The resolution would require the agreement of all five permanent members, each of which holds veto powers, but a text has not yet been shared, AFP reported.

(With input from Xinhua, AFP)