China has reported 27 new confirmed cases of the coronavirus as it tries to stem an upsurge in infections in a northeastern province bordering Russia.

Twenty of the new cases were in Heilongjiang province, including 13 Chinese nationals who had returned recently from Russia. The land border has been closed.

China's official death toll rose sharply to 4,632, reflecting a major upward revision of the previous day by authorities in Wuhan, the nation´s hardest-hit city.

Twenty of the new cases were in Heilongjiang province (pictured, a hospital in the city of Suifenhe), including 13 Chinese nationals who had returned recently from Russia

The land border between China and Russia (pictured at Suifenhe) has been closed due to the virus

In a social media post, the city government added 1,290 deaths to the tally in Wuhan, bringing the toll to 3,869.

Officials said many fatal cases were 'mistakenly reported' or missed entirely in an admission that comes amid growing global doubts about Chinese transparency.

The global pandemic originally emerged in Wuhan. The city went on to suffer the vast majority of China's fatalities from Covid-19, the disease caused by the virus.

The change also pushes the nationwide death toll up by nearly 39 percent, based on official national data released earlier on Friday.

Numbers of total cases in the city of 11million were raised by 325 to 50,333, accounting for about two-thirds of China's total 82,367 announced cases.

In a social media post, the city government added 1,290 deaths to the tally in Wuhan (pictured, today), bringing the toll to 3,869

China has come under increasing pressure over the coronavirus pandemic from Western powers led by the US. Pictured: In Wuhan

China has come under increasing pressure over the coronavirus pandemic from Western powers led by the US.

It has raised doubts about Chinese transparency and is probing whether the virus actually originated in a Wuhan laboratory.

China has said the virus emerged from a Wuhan food market whose merchandise reportedly included exotic wild animals sold for human consumption.

Wuhan's epidemic prevention and control headquarters cited several reasons for the missed cases, including the fact that the city's medical staff were overwhelmed in the early days as infections climbed, leading to 'late reporting, omissions or mis-reporting'.

Medical staff in Wuhan are seen removing the body of a person suspected to have the coronavirus in February at the height of the crisis

This photo taken on February 28, 2020 shows medical staff transferring a patient infected by the COVID-19 coronavirus at the Red Cross hospital in Wuhan in China's central Hubei province

It also cited insufficient testing and treatment facilities, and said some patients died at home and thus their deaths were not properly reported.

Top leaders of China´s ruling Communist Party called for steps to pump up the economy after the biggest downturn since the 1960s in the first three months of this year.

A Politburo meeting chaired by President Xi Jinping said yesterday the government must offset the impact of the pandemic with deficit spending and special bond issues.

The world´s second-largest economy shrank by 6.8 per cent from a year earlier in the first quarter of 2020.