The COVID-19 pandemic has exposed the "fragility of our world", according to the United Nations Secretary-General Antonio Guterres.

The 71-year-old made the remarks in Singapore where he addressed the Forum of Small States in commemorating the founding of the UN.

"Despite the enormous scientific and technological advances of recent decades, a microscopic virus has brought us to our knees," said Guterres.

"COVID-19 must be a wake-up call. It is time for an end to this hubris."

The UN chief’s remarks came as the number of COVID-19 infections globally surpassed 7.2 million with a death toll exceeding 413,000, according to the U.S.-based Johns Hopkins University.

Guterres said the damage caused by the pandemic is partly because countries embarked on different strategies to counter the virus rather than a unified response.

He called for unity in the world’s response to such and more tragedies including terrorism.

Guterres also warned that a second-wave of infections was possible if countries relaxed their responses to the pandemic.

Many countries across the world are already reopening and easing lockdown restrictions in a bit to enable resumption of normal life.

But Guterres said it was too early to relax.

"There is a real risk of a second wave. That is why we must insist that no country is safe and healthy until all countries are safe and healthy," he said.