President Donald Trump has said he will sign an executive order to temporarily suspend immigration into the US because of the coronavirus.

Posting on social media, Mr Trump said: “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!”

He gave no details about which immigration programmes might be affected by the order.

But much of the immigration system has already ground to a halt because of the pandemic.

Almost all visa processing by the State Department has been suspended for weeks. Travel to the US has been restricted from much of the globe, including China, Europe, Mexico and Canada.

Mr Trump has also used the virus to effectively end asylum at US borders, turning away even children who arrive by themselves – something Congress, the courts and international law had not previously allowed.

Criticism of his new announcement was swift, especially the timing during the pandemic. Ali Noorani, president of the National Immigration Forum, noted that thousands of foreign-born healthcare workers were currently treating people with Covid-19 and working in critical sectors of the economy.

Mr Trump’s call “ignores the reality of our situation,” he said. “The fact is that immigrants are standing shoulder-to-shoulder with US citizens on the front lines helping us get through this pandemic.”

Andrea Flores of the American Civil Liberties Union said: “Unfortunately, President Trump seems more interested in fanning anti-immigrant flames than in saving lives.”

But Jessica Vaughn, director of policy studies at the Centre for Immigration Studies, which favours lower rates of immigration, said that eliminating millions of work permits and visas would “instantaneously create” new jobs for Americans and other legal workers – even though most businesses are shuttered because of social distancing dictates and stay-at-home orders.

In a statement, White House press secretary Kayleigh McEnany described the order as aimed at protecting both the “health and economic well-being of American citizens as we face unprecedented times”.

“At a time when Americans are looking to get back to work, action is necessary,” she said without offering details on what programmes the order might cover and when it might be signed.

Though travel restrictions around the globe have dramatically reduced immigration, Mr Trump could use his executive authority to restrict it further, including slashing the number of foreign workers allowed to take seasonal jobs around the country.

Before the outbreak, the administration had planned to increased the number of H-2B visas, but the Department of Homeland Security put that increase on indefinite hold in early April.

Kevin Hassett, the former White House economic adviser who recently returned to help guide the response to the virus, said there would be “carve outs” for certain types of workers, but he cautioned: “We’ll have to wait and see what the final rule is going to be.”

National security adviser Robert O’Brien, meanwhile, compared the expected order to restrictions on travel to the US from China that Mr Trump put in place in January.

“We’re trying to do everything, the president’s trying to do everything he can to put the health of the American people first during this crisis,” Mr O’Brien said on Fox News.

Mr O’Brien said the administration believes the China restrictions saved lives.

Asked about Mr Trump’s reference to jobs, Mr O’Brien referenced the virus’ economic toll and said “the president’s looking out for Americans on both fronts at every turn”.

The US is now reporting more Covid-19 cases than any other country in the world, with almost 800,000 Americans infected, according to figures compiled by Johns Hopkins University. More than 42,000 have died.