TORONTO  - Five Canadian universities said on Wednesday that Saudi trainee doctors enrolled in their programs had been granted an extra three weeks in the country, a brief reprieve as a spat between the two countries forces nearly 1,000 people to leave their training early.

A call came this week from the Saudi Arabian Cultural Bureau, the organization that places hundreds of Saudi postgraduate medical students in Canadian hospitals, said Salvatore Spadafora, vice dean of post-MD education at the University of Toronto.

It was not immediately clear why the extension was granted. Students across Canada have scrambled to arrange their affairs and book flights out of the country. 

The extension comes two weeks after Saudi Arabia, furious at Canada's call for the release of arrested activists, ordered all Saudi students home by the end of the month.

Riyadh also froze new trade with Canada, expelled the country's ambassador and blocked imports of Canadian grain. 

"We have a verbal commitment... that there is an extension of the return-home date to September 22" from Aug. 31, Spadafora said, adding that the schools are awaiting written confirmation from the Saudi government that the trainees can stay.

An executive associate dean from the University of British Columbia said the school received a letter Wednesday from the Saudi Arabian Cultural Bureau confirming the extension and saying that students registered for exams Sept. 26-27 can remain in Canada to take them.

Dalhousie University in the eastern city of Halifax, McGill University in Montreal and McMaster University near Toronto, confirmed their Saudi students had received an extension.

Saudi Arabia is the largest source of foreign-trained medical residents and fellows in Canada, according to the Saudi Arabian Culture Bureau. It said 514 Saudis accounted for "over 95 percent" of the country's international residency spots in the coming academic year. 

"We remain hopeful there can be a resolution in the end that allows our learners to stay," Spadafora said.

(Reporting by Anna Mehler Paperny; editing by Dan Grebler and Cynthia Osterman) ((Anna.MehlerPaperny@thomsonreuters.com; +1-647-225-9609))