The US state of Missouri is suing China for inflicting “enormous death, suffering and economic losses” on the world.
Around 200 people have died from coronavirus in the Midwestern state, which is the first to sue the Chinese government over its handling of the outbreak.
However, China has called for solidarity and co-operation, saying it is not the time for “finger-pointing”.
The remarks were made by Consul-General Huang Ping as Beijing’s diplomats in New York handed over a donation of medical supplies to the city.
New York state has become a global hotspot for coronavirus with over 250,000 people testing positive and nearly 20,000 deaths.
Mr Huang said, in an online ceremony, that his president Xi Jinping and US counterpart Donald Trump “called for anti-epidemic co-operation between our two nations and the world” in their last phone call on 17 March.
He added: “As the two biggest economies in the world, China and the United States need to lead the effort to fighting the coronavirus.
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“This is not the time for finger-pointing. This is the time for solidarity, collaboration, co-operation and mutual support.”
The lawsuit, filed in federal court by the state’s top lawyer, alleges Chinese officials are “responsible for the enormous death, suffering, and economic losses they inflicted on the world, including Missourians”.
After weeks of elaborate praise of Mr Xi’s performance in the pandemic, Mr Trump has turned to blaming China and halting US contributions to the World Health Organisation, accusing it of parroting misinformation from Beijing.
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China’s UN Ambassador Zhang Jun stressed the importance of multilateralism, saying “we live in one world” and COVID-19 “knows no borders”.
He said: “We need to support the United Nations and the WHO in playing a leading and co-ordinating role in defeating COVID-19, the common enemy of all mankind.
“We should stand firm against the politicisation of the pandemic and remove all obstacles which hinder our co-operation.”
Mr Huang said the American people helped China “without hesitation” when it was in great difficulty, and its consulate and UN mission have donated 25,000 N95 masks, 2,000 protective suits, and 75,000 pairs of medical gloves, which reached New York last weekend.
Penny Abeywardena, New York City’s commissioner for international affairs, thanked China for its “extremely generous donation”, adding: “It is what our health care workers need and we are absolutely grateful that you are in this fight with us.”
After nearly two weeks of negotiations and deadlock, a near $500bn (£403bn) coronavirus aid package was approved by the US Senate on Tuesday, after Congress and the White House reached a deal to replenish a small business payroll fund and provided new money for hospitals and testing.
The package now goes to the House of Representatives.
Passage was swift and unanimous, despite opposition from conservative Republicans, and President Donald Trump tweeted his support, pledging to sign it into law.
“The Senate is continuing to stand by the American people,” said Senate majority leader Mitch McConnell.