President Donald Trump says he will suspend all immigration into the US temporarily through an executive order in response to the coronavirus outbreak and to protect jobs.

“In light of the attack from the Invisible Enemy, as well as the need to protect the jobs of our GREAT American Citizens, I will be signing an Executive Order to temporarily suspend immigration into the United States,” Mr Trump said in a tweet on Monday local time.

The coronavirus death toll across the US is 42,000 – the country has the world’s largest number of confirmed cases, with more than 780,000 infections, up by 27,000 on Monday local time.

At least 22 million Americans have applied for unemployment benefits in the past four weeks, triggering anti-lockdown protest marches across several states and bringing the US economy to a near standstill, with oil futures plunging to below zero.

The White House declined to offer further details of the reasoning behind Mr Trump’s decision, its timing, or its legal basis.

Residents line up in Detroit for food donations. Photo: Getty

The decision, which drew swift condemnation from Democrats, has effectively achieved one of Mr Trump’s long-term policy goals of curbing immigration – making use of the health and economic crisis that has swept the country as a result of the pandemic to do so.

Mr Trump said he was taking the action to protect the US workforce as millions of Americans lose their jobs amid the nationwide lockdowns.

Tweet from @realDonaldTrump

Meanwhile, Boeing and at least one other US heavy-equipment manufacturer have resumed production and some states have rolled out reopening plans – despite concerns there is not enough testing yet to keep the coronavirus from rebounding.

Boeing said it would put about 27,000 people back to work this week, building passenger jets at its Seattle-area plants. It will have “virus-slowing precautions” in place, including face masks and staggered shifts.

Doosan Bobcat, a farm equipment maker and North Dakota’s largest manufacturer, announced the return of about 2200 workers at three factories.

Businesses that start operating again in the US are likely to engender good will with the Trump administration at a time when it is doling out billions in relief to companies.

A businesses in Atlanta, Georgia, on Sunday. Photo: AAP

Mr Trump has been agitating to restart the economy, singling out Democratic-led states and egging on protesters who feel governors are moving too slowly.

Some states, mostly Republican-led ones, have relaxed restrictions. On Monday, some said they would take further steps to reopen their economies.

Georgia Governor Brian Kemp announced that gyms, hair salons, bowling alleys and tattoo parlours were among businesses that could reopen on Friday, as long as owners followed social distancing and hygiene requirements.

The governor said a decline in emergency room visits by people with flu-like symptoms indicated that infections were falling. But he also acknowledged that Georgia had lagged in COVID-19 testing and announced new initiatives to increase it.

A protest marches in Austin, Texas, against the coronavirus lockdown. Photo: Getty

On Monday, Texas began a week of slow reopenings, starting with state parks. Officials said shops would be allowed to offer kerbside service later in the week.

Tennessee Governor Bill Lee said businesses would begin reopening as early as next week, although the order did not cover counties with the largest cities, including Nashville, Memphis, Knoxville and Chattanooga.

Both Texas and Tennessee are governed by Republicans.

Mr Trump won the White House in 2016 in part on a promise to curb immigration by building a wall on the US border with Mexico. He and his advisers have spent the first three years of his tenure cracking down on legal and illegal entries into the country.

“You cut off immigration, you crater our nation’s already weakened economy,” former Democratic presidential candidate Julian Castro said in a tweet. “What a dumb move.”

Tweet from @JulianCastro

The US in mid-March suspended routine visa services, in most countries worldwide due to the coronavirus outbreak. The move has potentially impacted hundreds of thousands of people.

The administration recently announced an easing of rules to allow in more agricultural workers on temporary visas to help farmers.

-with AAP