Addressing the annual UN gathering of world leaders in New York, Guterres said images from some parts of the world of expired and unused vaccines in rubbish told "the tale of our times" - with the majority of the wealthier world immunised while more than 90 per cent of Africa has not even received one dose.

"This is a moral indictment of the state of our world. It is an obscenity. We passed the science test. But we are getting an F in ethics," Guterres told the UN General Assembly.

World leaders returned to New York this year after a virtual event last year during the pandemic.

As the coronavirus is still raging, about a third of the 193 UN states are again sending videos but presidents, prime ministers and foreign ministers for the remainder have travelled to the United States.

Out of 5.7 billion doses of coronavirus vaccines administered around the world, only 2 per cent have been in Africa.

Guterres is pushing for a global plan to vaccinate 70 per cent of the world by the first half of next year.

The World Health Organisation has asked governments to hold off on booster shots until more people worldwide receive their initial doses.

But a growing list of countries including the UK, Chile, Germany and Israel have decided to offer booster doses to older citizens or people with weak immune systems in the face of the fast-spreading Delta variant.

WHO officials say the science is unproven about whether giving booster shots to people who have already received two vaccine doses is effective in preventing the spread of the coronavirus.

with AP

Australian Associated Press