"We expect to reach a total of 10 million cases within the next week".
Officials of the agency during a virtual briefing from Geneva on Monday said this was the largest single-day increase of the virus since it was first detected in Wuhan, China.
WHO's DG Dr Tedros Adhanom Ghebreyesus said the greatest threat was not the virus itself, which has now killed over 470,000 people (at press time), but "the lack of global solidarity and global leadership".
Almost half of Sunday's record number of cases were recorded in Brazil and the US, the two countries that also have the highest COVID-19 death tolls in the world.
"All countries are facing a delicate balance between protecting their people while minimizing the social and economic damage", he said.
He said governments across the world must be "careful and creative" in finding solutions so that people stay safe while getting on with their lives. He also urged individuals to maintain proper physical distancing, wash their hands with soap regularly and wear a mask when appropriate.
'At the same time, these measures can only be effective if each and every individual takes the measures that we also know work to protect themselves and others: Maintain physical distance; Continue cleaning your hands; And wear a mask where appropriate, ' World Health Organization director-general said.
UEFA announce dates and format for Champions League and Europa League
UEFA have announced changes to next seasons Champions League qualifiers and they will have huge ramifications for Celtic. Petersburg, Russia, will instead be the site in 2022.
Ghebreyesus added: "The next challenge is to increase production and then quickly and equitably distribute dexamethasone worldwide, focusing on where it is needed most".
"We've seen a steady and worrying continuation of trend, with many countries experiencing between a 25 and 50 percent rise in cases over the last week".
He said that fortunately, dexamethasone is an cheap drug and many manufacturers worldwide can likely accelerate production.
Demand has already surged following trials in the United Kingdom, he said.
"There is no evidence that dexamethasone works for patients who are only mildly affected, or as a preventative measure".
Mexico City has delayed reopening markets, restaurants, malls, hotels and places of worship, with the country now recording over 20,000 Covid-19 deaths. World Health Organization is now in the process of shipping more than 140 million items of personal protective equipment to 135 countries, 14,000 oxygen concentrators and millions of tests.