Asian equities soared again Wednesday after US lawmakers finally agreed a mammoth stimulus package to support the world's top economy against the impact of the coronavirus pandemic.

While the deadly disease continues to spread, traders have a rare semblance of optimism after weeks of carnage across global markets, with eyes fixed on Washington where lawmakers in the early hours thrashed out an emergency bill worth as much as $2 trillion -- around 10 percent of US gross domestic product.

"At last, we have a deal," Senate Majority Leader Mitch McConnell said, citing the massive "wartime level of investment into our nation".

The prospect of a massive spending splurge, combined with the Federal Reserve's pledge to essentially print as much cash is needed, sent Wall Street into overdrive Tuesday, with the Dow seeing its biggest rise since 1933, while the S&P 500 enjoyed its best day in more than a decade.

And the gains spread into Asia, which rallied for a second straight day, with extra impetus later in the day coming from the news out of Washington.

Tokyo ended eight percent higher, with investors there also relieved that the 2020 Olympics had been postponed rather than cancelled.

Hong Kong, Shanghai and Singapore climbed more than two percent, Sydney and Manila rallied more than five percent and Seoul piled on more than four percent.

Taipei added almost four percent, while Bangkok and Wellington were also well up.

Adding to the more upbeat mood was the G7's promise to do "whatever is necessary".

The unprecedented moves are part of a worldwide response to the rapid financial shock caused by the COVID-19 outbreak, which has locked down countries including the US and brought the global economy to a juddering halt.

"Risk assets are enjoying a nice rebound as the market digests the Fed's broadening QE move into the corporate space while the prospect of a big US fiscal stimulus edges closer to fruition," said National Australia Bank's Rodrigo Catril.

Hopes for the US deal and the Fed's promise to ramp up its bond-buying, also sent the dollar lower, a relief to investors as demand for the unit had seen it soar against peers, including a 35-year high against the pound.

The crude market -- which has been hammered by the outbreak's impact on demand, as well as a price war between Saudi Arabia and Russia -- also enjoyed a much-needed lift, though analysts cautioned the commodity still faced uncertainty.

However, observers warned that world markets were not out of the woods just yet as the number of infections and deaths continues to rise rapidly and the full economic impact is still unknown.

Countries around the world have gone into lockdown to prevent the spread of the virus, bringing the global economy to a virtual standstill
Countries around the world have gone into lockdown to prevent the spread of the virus, bringing the global economy to a virtual standstill AFP / Johan ORDONEZ

"In 'buy the rumour, sell the news' fashion, the stock market could easily take another sharp leg lower once the good news is out, and investors conclude that it won't be enough (yet) to address what's going on in the real economy," said AxiCorp's Stephen Innes.

"Given the rapid succession of downgrades, we should likely expect more pain over the short term, as the situation in New York and California continues to deteriorate. And with the entire population of India going into a government-enforced a 21-day nationwide curfew, it doesn't suggest blue sky."

Still, he did say that the US package "should be sufficient to avoid buttress Main Street from falling into a worst-case depression type scenario".

Tokyo - Nikkei 225: UP 8.0 percent at 19,546.63 (close)

Hong Kong - Hang Seng: UP 2.7 percent at 23,264.71

Shanghai - Composite: UP 2.1 percent at 2,779.21

Brent North Sea crude: UP 3.4 percent at $28.08 per barrel

West Texas Intermediate: UP 4.0 percent at $24.97

Euro/dollar: UP at $1.0816 from $1.0782 at 2100 GMT

Dollar/yen: DOWN at 111.23 yen from 111.32 yen

Pound/dollar: UP at $1.1849 from $1.1754

Euro/pound: DOWN at 91.28 pence from 91.75

New York - Dow: UP 11.4 percent to 20,704.91 (close)

London - FTSE 100: UP 7.5 percent at 5,367.45 points (close)