The World Health Organisation chief warned reporters on Monday that “the worst is yet ahead of us” in the coronavirus pandemic, reviving the alarm just as many countries ease restrictive measures aimed at reducing its spread.

WHO Director General Tedros Adhanom Ghebreyesus didn’t specify why he believes the outbreak, which has infected about 2.5 million people and killed more than 166,000, would get worse. But he and others have previously pointed to the spread of the illness through Africa, where health systems are far less developed.

“Trust us. The worst is yet ahead of us,” Tedros told reporters from WHO headquarters in Geneva. “Let’s prevent this tragedy. It’s a virus that many people still don’t understand.”

Some Asian and European governments have gradually eased or started to relax “lockdown” measures such as quarantines, school and business closures and restrictions on public gatherings, citing a decline in the growth of Covid-19 case counts and deaths.

Mr Tedros and his agency have been on the defensive after President Donald Trump of the United States – the WHO’s biggest single donor – last week ordered a halt to US funding for the agency, saying it had botched its early response to the outbreak.