An Iranian British Columbia resident who has studied and worked in Canada for five years says he was blocked from boarding a flight to Las Vegas on Saturday, one day after U.S. President Donald Trump issued an executive order banning visitors from several predominantly Muslim countries.

Mohammad Rafatinasr, 32, a mechanical engineer, was set to fly to Las Vegas to present a paper at a research conference.

But an airlines official informed him that he was was not permitted to enter the United States after he approached the departure gate at Vancouver International Airport.

"I was a bit shocked," he said.

Obtained U.S. visa, bought ticket

Rafatinasr, who is in Canada on a post-graduation work permit and who moved to Canada in 2012, said he applied for a U.S. visa three months earlier and received it last week. He lives in  Port Moody, B.C., and works in nearby Vancouver.

On Friday, Trump issued an executive order barring citizens from seven Muslim-majority countries — including Iran — from entering the U.S.

Rafatinasr said he hoped he'd still be allowed to fly to the U.S., but  knew something was wrong when he was unable to check in online.

At the airport, he tried to check in again, this time in person. He was booked on an Air Canada flight and presented his passport and visa.

But when an airline official ran his passport through a computer scanner, she told him he was "inadmissable."

Rafatinasr asked why, repeating he had received a visa from the U.S. consulate just days before but the agent had no answer.

"After three months waiting for a visa and then suddenly ... 'Oh, your place of birth indicates that you are not allowed to enter,' " Rafatinasr said.

Rafatinasr, who earned a PhD from the University of Saskatchewan, said he arranged for a former colleague and supervisor from the university to present his work instead.

"It's disappointing for me that I am not able to be there to express my work myself," Rafatinasr said.

He has won several awards and fellowships for his research, which is focused on helping to reduce energy requirements for heating indoor buildings in cold regions.

Canada's immigration minister said on Sunday that Canadian permanent residents would be permitted to travel freely to the U.S. 

Rafatinasr is married and plans to stay in Canada and apply for permanent resident status.