US President Donald Trump says the US will suspend all travel from Europe to the United States for the next 30 days because of the Covid-19 coronavirus.

Photo: AFP

But he said the "strong but necessary" restrictions would not apply to the UK, where 460 cases of the virus have now been confirmed.

There are 1135 confirmed cases of the virus across the US, with 38 deaths.

"To keep new cases from entering our shores, we will be suspending all travel from Europe to the United States for the next 30 days," Trump said.

"The new rules will go into effect Friday at midnight," he added.

"We are marshalling the full power of the federal government and the private sector to protect the American people," he said.

"This is the most aggressive and comprehensive effort to confront a foreign virus in modern history," he said.

Trump, whose re-election bid on 3 November could hinge on how well he responds to the crisis, stopped short of declaring a national emergency.

But he pulled no punches in saying Europe was partly to blame for the virus's spread in the United States. His travel restrictions on Europe were similar to what he declared on travel from China when the illness was spreading wildly there.

"The European Union failed to take the same precautions and restrict travel from China and other hot spots. As a result, a large number of new clusters in the United States were seeded by travellers from Europe," he said.

As the US stock market took another hit from the virus on Wednesday, Trump said he would take emergency action to provide financial relief for workers who are ill, quarantined or caring for others due to the illness.

He said he was instructing the Treasury Department to defer tax payments without interest or penalties for certain businesses and individuals affected.

Trump added he was also instructing the Small Business Administration to provide capital and liquidity to firms affected by the virus.

He urged Congress to pass tax relief measures in an attempt to combat the effect of the outbreak on the US economy.

"I am calling on Congress to provide Americans with immediate payroll tax relief," he said.

Trump said the situation was not a financial crisis, but global shares crumbled after Trump's announcement. US S&P500 futures dropped more than 3 percent, a day after the S&P 500 lost 4.89 percent, putting the index in bear market territory, defined as a 20 percent fall from a recent top.

Euro Stoxx 50 futures dived more than 5 percent to their lowest levels since mid-2016. MSCI's broadest index of Asia-Pacific shares outside Japan dropped 2 percent to its lowest level since early 2019, while Japan's Nikkei lost 3.3 percent.

What is the situation in the US?

Officials said the risk of infection was low for the general US public, but concern deepened after a number of new cases were confirmed earlier this month.

Containment efforts have begun in earnest. Troops have been deployed to New Rochelle, just north of New York City, where one outbreak is believed to have originated.

The National Guard will deliver food to some individuals who have been told to self-isolate there.

The governor of Washington state has banned large gatherings in several counties. The north-western state is the focal point of the outbreak in the US, accounting for 24 of at least 38 deaths across the country.

New Zealand politicians respond

Health Minister David Clark will be seeking advice from experts as the US announces a travel ban with Europe.

Speaking soon after the announcement, Clark said New Zealand benefited from early travel restrictions.

He said there had been daily reviews with regular updates of medical and scientific advice.

"I'm very aware of the fact that they have been monitoring the US, they have been monitoring Europe and they have been keeping us updated and we have questions along the way and I expect we will get updated advice again today," Clark said.

The US was in a different situation than New Zealand, because it now has a community outbreak.

Meanwhile, Foreign Affairs Minister Winston Peters said it was not his place to pass any judgement on the United States' decision to halt travel from Europe.

Peters said every country had to decide on its own response.

He would not be drawn on the impact of Trump's decision on international relations.

"Well, that's a fact that the pandemic nature has been recognised by the WHO and the Americans have acknowledged where they think their concerns lie and every country in the world has got to have a response and I believe our country, New Zealand, has been way ahead of most."

He also would not comment on whether New Zealand should follow suit, saying that was a matter for the Cabinet sub-committee to consider based on advice from health and science officials.

NBA suspended

Meanwhile, the NBA has suspended its season.

The announcement came shortly after a game between the Utah Jazz and the host Oklahoma City Thunder was called off moments before tipoff.

According to the NBA, a Jazz player preliminarily tested positive for coronavirus. The NBA stated the affected player was not in the arena at the time.

If you have symptoms of the coronavirus, call the NZ Covid-19 Healthline on 0800 358 5453 (+64 9 358 5453 for international SIMs)

Read more about the Covid-19 coronavirus: