Hundreds of Canadians working for technology companies or multinational corporations in the United States could be affected by a new ban that freezes the issuance of temporary work visas until the end of the year.

The Trump administration on Monday extended a ban on green cards issued outside the U.S. and added many temporary work visas to the freeze. The ban on new visas, which takes effect Wednesday, applies to four categories including H-1B, H-2B, J-1, and L-1.

Scotty Greenwood, the CEO of the Canadian American Business Council, said her group is "extremely concerned" about the move, and she's already heard from members of her organization unhappy with the ban.

"I have to believe that the executive order wasn't intended to target Canada but nevertheless it impacts Canada-U.S. commerce and that's unfortunate and I hope can be rectified in some way," Greenwood said.

According to documents provided by the U.S. State Department, more than 400 Canadians were issued the affected visas in 2019.

The H-1B, which is widely used by American and Indian technology companies, was issued to 101 Canadians in the 2019 fiscal year. The J-1, for "cultural exchange," was issued to 156 Canadians.

The L-1, which applies to managers and other key employees of multinational corporations, was issued to 161 Canadians, and the H-2B, for non-agricultural seasonal workers, was issued to five Canadians.

But conflicting figures reported by the Department of Homeland Security put the numbers much higher. That department says more than 4,600 Canadians were issued new or renewed visas last year in the H-1B class alone.

The Trump administration cast the effort as a way to free up jobs in an American economy reeling from the COVID-19 pandemic. A senior official who spoke to reporters on condition of anonymity predicted it will open up to 525,000 jobs for Americans.

Greenwood said the executive order is ill-suited to opening up jobs for Americans since the visas were often used for limited jobs. She gave the example of a Canadian engineer travelling into the U.S. to repair a specialized piece of equipment on an urgent basis for a week or two before returning home.

"That doesn't jeopardize a U.S. job, it's just part of the normal flow of business," said Greenwood.

Two other vocal critics were Shopify vice-president and general manager Kaz Nejatian, as well as founder and CEO Tobi Lutke. Both criticized the executive order on Twitter and offered people the opportunity to apply to work for the Canadian tech firm.

"We believe commerce needs more voices, not fewer. And that means pursuing, not hindering, highly skilled people from all corners of the world," Nejatian said in a statement.

The ban, while temporary, represents a cut to legal immigration on a scale that had eluded the administration before the pandemic. Long-term changes that would prevent many asylum seekers from getting work permits and would allocate high-tech worker visas differently are also being sought.

Business groups pressed hard to limit the changes but got little of what they wanted, marking a victory for immigration hardliners as U.S. President Donald Trump seeks to further solidify their support ahead of the November election.

There will be exemptions for food processing workers, which make up about 15 per cent of H-2B visas, an official told The Associated Press. Health-care workers assisting with the coronavirus fight will continue to be spared from the green-card freeze, though their exemption will be narrower.

Trump imposed a 60-day ban on green cards issued abroad in April, which was set to expire Monday. That announcement, which largely targeted family members, drew a surprisingly chilly reception from immigration hardliners, who said the president didn't go far enough.

The freezes on visas issued abroad are designed to take effect immediately. Other changes, including restrictions on work permits for asylum seekers, will go through a formal rule-making process that takes months.

Dan Revich, a Canadian practising immigration law in Los Angeles, said that although he expected there would be an extension on the ban, he was surprised by the breadth of it and that it would be in place until Dec. 31.

"We're waiting on a lot of guidance from the government agencies to figure out exactly how they're going to interpret this," said Revich. "But I would say that any Canadians who are worried about this should definitely keep track of what's happening and make sure to talk to a lawyer before trying to do any travelling."

-- With files from The Associated Press.

This report by The Canadian Press was first published on June 23, 2020.