The organisation reported on Friday the highest number in terms of new coronavirus cases ever recorded, warning that the pandemic is exposing migrants to "an even more severe hardship".
The coronavirus pandemic is "accelerating", the World Health Organisation (WHO) warned.
The WHO's Director-General told reporters on Friday that more than 150,000 new cases of COVID-19 were recorded in the past 24 hours, in what was the highest number of new infections per single day on record.
Nearly half of the newly reported cases were from the Americas, with Brazil announcing it passed one million cases, but significant numbers also came from South Asia and the Middle East.
In Africa - where the number of coronavirus infections recently topped 200,000 - South Africa alone accounts for around 30% of the continent's cases - only second to Egypt for number of deaths, despite imposing one of the world's strictest lockdowns. On Friday, the country reported 4,000 new COVID-19 cases.
"The world is in a new and dangerous phase," Tedros Adhanom Ghebreyesus stated, adding that confinement measures, such as social-distancing, mask-wearing and hand-washing, are still needed to halt the pandemic.
He also addressed his concerns over "the very real and present danger of widespread transmission of COVID-19 in refugee camps, where the pandemic "is exposing many refugees to even more severe hardship".
"We have a shared duty to do everything we can to prevent, detect and respond to the transmission of COVID-19 among refugee populations," Ghebreyesus stressed.
Over 8.6 million cases have been reported globally since the beginning of the pandemic, and more than 460,000 lives have been lost, according to the Johns Hopkins Coronavirus Resource Center.
The US remains the worst-hit country, accounting for 119,000 deaths, followed by Brazil, with nearly 49,000 fatalities.
There is still no vaccine for coronavirus, however this week scientists in the UK found that a low-cost steroid called dexamethasone may reduce mortality by up to a third in COVID-19 patients with severe respiratory complications.