US President Donald Trump has signed into law a $2 trillion rescue plan to salvage the US economy crippled by the coronavirus pandemic.

The United States has recorded more than 100,000 confirmed cases of virus infections and almost 1,700 deaths.

The House of Representatives passed the package, with legislators uniting to approve the plan.

Mr Trump's signature triggers the distribution of millions of relief cheques of up to US$3,400 for an average American family of four.

He said: "I want to thank Democrats and Republicans for coming together and putting America first.

"This will deliver urgently needed relief to our nation's families, workers and businesses. That's what this is all about."

The president also took the step of invoking the Defense Production Act to compel car maker, General Motors, to quickly honour its commitment to making ventilators, machines crucial to keeping critically ill coronavirus patients alive, but which are in short supply in US hospitals.

The need is acute in New York state, the US epicentre of the epidemic where 44,635 infections have been confirmed.

The number of deaths there increased yesterday to 519 - up from 385 the previous day - but Governor Andrew Cuomo expressed optimism that the increase in the hospitalisation rate has slowed.

He announced the creation of temporary hospitals in large facilities in each borough of New York City - including at a horse racing track in Queens - in the model of an already-constructed space in Manhattan's Javits Center.

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The bill pumps $100 billion into hospitals and health facilities in critical need of medical equipment like personal protective equipment and intensive care beds, creates a $500 billion loan reserve for large corporations including airlines, and provides $377 billion in grants to small businesses.

It also dramatically expands unemployment assistance, aid that will cushion the blow for 3.3 million people who filed jobless claims in the week ending 21 March.

House Speaker Nancy Pelosi said shortly before the measure was passed, that the US faced an economic and health emergency of historic proportions due to the coronavirus pandemic, the worst pandemic, she said, in more than 100 years.