The number of confirmed coronavirus cases worldwide has topped 16 million.

According to a tally by Johns Hopkins University, the US leads the count with 4.1 million, followed by 2.3 million in Brazil and 1.3 million in India.

The US also has the highest number of deaths with 146,460, followed by 86,449 in Brazil and 45,823 in the UK.

In the US, New York state leads with 32,608 deaths.

North Korean leader Kim Jong Un said he believes "the vicious virus" may have entered the country, and placed the city of Kaesong, near the border with South Korea, under total lockdown after a person was found with suspected Covid-19 symptoms.

In South Korea, the number of new cases fell back to below 60, a day after it reported 100-plus for the first time in nearly four months.

Health authorities said the 113 cases on Saturday were mostly imported infections found among cargo ship crews and hundreds of South Korean construction workers airlifted out of virus-ravaged Iraq.

Vietnam reimposed restrictions in one of its most popular beach destinations after a second person tested positive for the virus, the first locally transmitted cases in the country in more than three months.

Authorities in Da Nang banned gatherings of more than 30 people in public places as well as all sport, cultural and religious events in the city of 1.1 million. Theme parks, beauty salons, bars and clubs were also ordered to shut.

On Sunday, a 61-year-old man was confirmed to be infected, a day after a 57-year-old tested positive for the coronavirus. Both are in a critical condition and require life support.

A team of doctors who successfully cured a British pilot of Covid-19 flew to Da Nang to direct the treatment of the two patients.

Health workers, however, have not been able to establish a connection between the two men, nor trace the source of infection.

Several hundred people who had been in contact with the men have initially tested negative for the virus. The city has also started testing on a larger scale.

The new infections take Vietnam's cases to 418 with no deaths.

China reported 46 new Covid-19 cases on Sunday, the highest daily tally in more than a month, as it took steps to stem recent outbreaks that have infected more than 160 people at opposite ends of the country.

China has recorded 83,830 cases and 4,634 deaths since the pandemic began. The Health Commission said that 288 patients remain in treatment, including 18 in a critical condition.

In Australia, Victoria state recorded 10 deaths overnight - its highest daily toll amid a continuing surge in cases.

State Premier Daniel Andrews said the deaths included seven men and three women. A man in his 40s became one of the youngest Covid-19 fatalities in Australia.

There were 459 new infections, the 21st straight day of triple-figure increases.

The deaths take Victoria's toll to 71 and Australia's national tally to 155. A total of 228 people are in hospital in Victoria, 42 of them in intensive care.

Victoria processed 42,973 tests on Saturday, Mr Andrews said, "far and away the biggest testing result that we've seen on a single day".

He said he is not currently planning to extend the lockdown in Melbourne, Australia's second-largest city.