Tedros Adhanom Ghebreyesus told a virtual health forum organized by Dubai authorities that the greatest threat facing the world is not the virus itself, but "the lack of global solidarity and global leadership". 

"We cannot defeat this pandemic with a divided world," he said. 

"The politicization of the pandemic has exacerbated it. None of us is safe until all of us are safe."

The WHO warned last week of a new and dangerous phase of the coronavirus pandemic, with people tiring of lockdowns despite the disease's rapid spread.

The COVID-19 illness, which has now killed more than 465,000 people and infected almost nine million worldwide, is surging in the Americas and parts of Asia, even as Europe starts to ease restrictive measures. 

Lockdowns imposed to halt the spread of the virus have caused crippling economic damage, but the WHO says the pandemic still poses a major threat. 

"The pandemic is still accelerating," Tedros told the virtual conference.

"We know that the pandemic is much more than a health crisis, it is an economic crisis, a social crisis, and in many countries a political crisis," he said.

"Its effects will be felt for decades to come."

A vaccine remains months off at best despite several trials, while scientists are still discovering more about the virus, its symptoms and the extent to which it may have spread before being identified.