New cases of Covid-19 are "accelerating" out of control across most of the world, the head of the World Health Organisation (WHO) has warned.

Dr Tedros Adhanom Ghebreyesus said the total number of cases of coronavirus worldwide has doubled in the past six weeks to reach 11.8 million.

Tedros said the pandemic was worsening and showed no signs of slowing in the hardest-hit countries: the US, Brazil and India.

Between them, the three countries recorded 129,000 new daily virus cases on Thursday; the US was the highest at 59,000.

Advertisement

Speaking at the member state briefing on the pandemic, Tedros said: "The virus has up-ended health systems in some of the world's wealthiest nations.

"Some countries that have mounted a successful response have been of modest means.

"We know that when countries take a comprehensive approach based on fundamental public health measures – such as find, isolate, test and treat cases, and trace and quarantine contacts – the outbreak can be brought under control.

"But in most of the world the virus is not under control. It is getting worse.

WHO director general Tedros Ghebreyesus has warned coronavirus is accelerating out of control globally. Photo / AP
WHO director general Tedros Ghebreyesus has warned coronavirus is accelerating out of control globally. Photo / AP

"More than 11.8 million cases of Covid-19 have now been reported to WHO.

"More than 544,000 lives have been lost.

"And the pandemic is still accelerating."

The worst hit country, the US, is approaching the grim milestone of almost one in every hundred people infected with Covid-19.

Advertisement

This week India, which has a population of 1.35 billion, reported nearly 25,000 new coronavirus infections, bringing the total to 767,296.

India's infection numbers have skyrocketed since the government eased lockdown restrictions and as testing has ramped up to more than 200,000 samples a day.

However, health experts say the true extent of the virus's spread in India is unknown.

Health workers arrive to screen people for Covid-19 symptoms at a slum in Mumbai, India. Photo / AP
Health workers arrive to screen people for Covid-19 symptoms at a slum in Mumbai, India. Photo / AP

Brazil reported nearly 45,000 new cases and in other South American countries, like Bolivia and Venezuela, the numbers continue to climb.

Bolivia has 42,984 confirmed cases and 1577 deaths.

In Europe, where many countries are reporting a decline, new hot spots have emerged, such as in Serbia where a spike in numbers is being blamed on the lifting of restrictions.

Advertisement

A ban on gatherings in the capital, Belgrade, and a limit on cafe and nightclub operations is expected to be ordered to try and rein in the spread of infection.

A health worker takes a blood sample from a boy during door-to-door testing and screening for the coronavirus in Pakistan. Photo / AP
A health worker takes a blood sample from a boy during door-to-door testing and screening for the coronavirus in Pakistan. Photo / AP

Serbia has confirmed more than 17,000 cases in a population of almost seven million and its prime minister has admitted the capital's health system is "close to breaking".

While other places, like Victoria, are treating with alarm outbreaks which seem mild by comparison to the likes of the US and Brazil, the virus' infectiousness underlines the WHO's latest announcement.

Tokyo confirmed it has a "wake-up call" of 220 new infections, exceeding its record daily increase from mid-April and prompting concerns of widening of the infections.

Hong Kong has tightened social distancing rules after a reported 42 new infections on Thursday.

Tedros' warning came as US President Donald Trump has announced his country will begin its formal withdrawal from the WHO.

Advertisement