The United Nations chief welcomed the Biden administration's announcement that it will be donating millions of doses of Covid-19 vaccine to the UN-backed Covax facility as well as to individual countries and UN frontline personnel in challenging and dangerous locations.

UN spokesman Stephane Dujarric says Secretary General Antonio Guterres is also "extremely grateful to the US government for including UN personnel and diplomats and staff of the 193 UN member nations in the US vaccination programme".

Dujarric said the donation to UN frontline personnel will allow staff members to stay and deliver critical services to vulnerable people around the world in a safe and effective manner, AP reports.

Biden had announced on Thursday that the US will swiftly donate an initial allotment of 25 million doses of surplus vaccine overseas through the Covax programme.