Confirmed Covid-19 infections are nearing the one million mark after “near exponential growth” saw global cases more than double in the past week.

The World Health Organization chief, Tedros Adhanom Ghebreyesus, warned of the approaching milestone as new cases reached almost every country and territory across the world.

“As we enter the fourth month since the start of the Covid-19 pandemic I’m deeply concerned about the rapid escalation and global spread of infection,” Tedros said.

“Over the past five weeks, we have witnessed a near exponential growth in the number of new cases, reaching almost every country.

“The number of deaths has more than doubled in the past week. In the next few days we will reach one million confirmed cases and 50,000 deaths.” The total number of cases on Thursday was just below 936,000 with more than 47,000 deaths.

On Wednesday evening, Donald Trump warned of “difficult days” for the US, saying: “We are going to have a couple of weeks, starting pretty much now, but especially a few days from now, that are going to be horrific.”

He again questioned China’s reported numbers on the virus: “The numbers seem to be a little bit on the light side – and I am being nice when I say that – relative to what we witnessed and what was reported.”

The comments followed a Bloomberg news story that said a classified US intelligence report had concluded that China had under-reported the total cases and deaths it had suffered. On Wednesday – the last day of available figures – China reported 82,361 confirmed cases and 3,316 deaths.

Trump’s warning came as the Federal Emergency Management Agency (FEMA) reportedly asked US defence agencies for 100,000 body bags, for use by civilian authorities. The White House has previously said deaths could reach 240,000.

New York mayor Bill de Blasio holds a media briefing on a tennis court at the Billie Jean King National Tennis Center, where a 350-bed temporary hospital will be built. Photograph: Erik Pendzich/REX/Shutterstock

The United States has reported 213,000 confirmed cases – more than 20% of cases globally. Their death toll stands at 5,119.

The rapid growth in the number of infections has overwhelmed hospitals in many cities. A week ago the US Centers for Disease Control said there were 85,000 cases. That means recorded cases have grown by two and a half times in a week, and up from 15,219 two weeks ago.

Workers wearing protective suits pray before a disinfection operation in Kuala Lumpur Photograph: Lim Huey Teng/Reuters

In Europe, the three worst-affected countries – Italy Spain and Germany – represent just under a third of the confirmed cases worldwide, according to Johns Hopkins University figures. Their combined death tolls make up 44% of fatalities worldwide.

Spain hit another grim milestone on Thursday, as the number of deaths passed 10,000 and yet another record single-day death toll of 950 was recorded. However, while the total number of cases in the country rose to 110,238, the spread of the disease appears to be continuing to slow during the so-called “stabilisation phase”.

In Italy there is growing concern over social unrest, three weeks into its lockdown. Tensions in some of the poorest southern regions of Campania, Calabria, Sicily and Puglia have mounted, as people in some areas began to run out of food and money.

Meanwhile Russia posted its largest single-day rise in identified cases. Officials said they had identified 771 new cases in the past day, a 28% rise from the previous day. Nearly 600 of the new cases were in Moscow, which has been the Russian city hit hardest by the crisis, with 2,475 confirmed cases. So far, 30 people have died, official statistics report.

Other coronavirus developments included: