The US on Monday said it would not allow foreign students to remain in the country if all of their classes are moved online in the fall because of the coronavirus crisis.

US Immigration and Custom Enforcement (ICE) said in a statement: “Nonimmigrant F-1 and M-1 students attending schools operating entirely online may not take a full online course load and remain in the US.

“Active students currently in the US enrolled in such programmes must depart the country or take other measures, such as transferring to a school with in-person instruction to remain in lawful status.

“If not, they may face immigration consequences including, but not limited to, the initiation of removal proceedings.”

ICE said the State Department “will not issue visas to students enrolled in schools and/or programmes that are fully online for the fall semester nor will US Customs and Border Protection permit these students to enter the US”.

F-1 students pursue academic coursework and M-1 students pursue “vocational coursework”, it said.

Universities with a hybrid system of in-person and online classes will have to show that foreign students are taking as many in-person classes as possible, to maintain their status.

Critics quickly hit back at the decision.

Senator Bernie Sanders tweeted: “The cruelty of this White House knows no bounds.

“Foreign students are being threatened with a choice: risk your life going to class-in person or get deported.”

For Gonzalo Fernandez, a 32-year-old Spaniard doing his doctorate in economics at George Washington University in the US capital, “the worst thing is the uncertainty.

“We don’t know if we will have classes next semester, if we should go home, if they are going to throw us out.”

Most US colleges and universities have not yet announced their plans for the fall semester.

Several schools are looking at a hybrid model of in-person and online instruction but some, including Harvard University, have said all classes will be conducted online.

Harvard said 40 per cent of undergraduates would be allowed to return to campus – but their instruction would be conducted remotely.

There were more than one million international students in the US for the 2018-2019 academic year, said the Institute of International Education (IIE).

That accounted for 5.5 per cent of the total US higher education population, the IIE said, and international students contributed $44.7 billion to the US economy in 2018.

The largest number of international students came from China, followed by India, South Korea, Saudi Arabia and Canada.

Aaron Reichlin-Melnick, who works as the policy counsel at the Washington-based think tank American Immigration Council, said the new rule is “almost certainly going to be challenged in court”.

He explained on Twitter that foreign students will likely struggle to continue their studies while abroad, due to time differences or a lack of access to technology or academic resources.

President Donald Trump, who is campaigning for re-election in November, has taken a bullish approach to reopening the country even as virus infections continue to spike in parts of the country, particularly the south and west.

He tweeted on Monday: “SCHOOLS MUST OPEN IN THE FALL!!!”

With more than 130,000 deaths linked to the novel coronavirus, the US is the hardest-hit country in the global pandemic.

While cracking down on immigration is one of his key issues, Trump has taken a particularly hard stance on foreigners since the health crisis began.

In June, he froze until 2021 the issuing of green cards – which offer permanent US resident status – and some work visas, particularly those used in the technology sector, with the stated goal of reserving jobs for US citizens.