The World Health Organisation is accused of conspiring with the Chinese government to cover up the severity of the coronavirus pandemic, according to a class-action lawsuit filed in New York.

Residents from one of the earliest and hardest-hit counties in the US claim the World Health Organisation (WHO) failed to quickly declare a pandemic, monitor China's response to the outbreak, provide treatment guidelines, advise members on how to respond including through travel restrictions, or coordinate a global response.

The WHO on 14 January tweeted that there was no clear evidence of human-to-human transmission of the novel virus identified in Wuhan, China.

That position was cited by Donald Trump when announcing the US's 60-90 day review of the agency, saying it failed to investigate credible reports in December 2019 from sources in Wuhan that conflicted directly with the Chinese government's official accounts.

Kling et al v World Health Organisation was filed in the US District Court, Southern District of New York, by Westchester residents Richard Kling and Steve Rotker, of New Rochelle, and Gennaro Purchia, of Scarsdale.

New Rochelle became an early coronavirus hot spot after a lawyer tested positive for Covid-19 on March 2. A total of 23,803 have tested positive in Westchester, and 242,786 in New York, through to April 18, according to the state's health department.

With 17,671 deaths in total, New York State is the hardest-hit region of the United States' 775,846 cases and 41,302 deaths.

The lawsuit accuses the World Health Organisation of gross negligence and seeks damages for what the plaintiffs call "incalculable" harm to the 756,000 adult residents in the county that would be part of the class action.

While China is not named as a defendant, the country faces multiple private lawsuits in the US seeking damages related to the pandemic.

The World Health Organisation did not immediately respond to email requests for a response to the lawsuit.