Saudi Arabia barred all citizens from receiving medical treatment in Canada as a diplomatic dispute over criticism of its human rights record intensifies, reported Al-Jazeera.

Riyadh also announced it is coordinating the transfer of all Saudi patients from Canadian hospitals to other medical facilities outside Canada, the Saudi press agency reported on Wednesday.

Saudi Arabia expelled Canada's ambassador, recalled its own envoy, and cut trade ties with Canada after it publicly denounced a crackdown on rights activists in the Gulf kingdom on Twitter.

The sharp diplomatic dispute between the two countries has left the United States - partner and ally of both - in a bind.

"Both sides need to diplomatically resolve this together. We can't do it for them," Heather Nauert, State Department spokeswoman, said.

Saudi Arabia expels Canadian ambassador over criticism of arrests

Washington "raised" the case with Riyadh, she said, adding: "The United States has respect for internationally recognised freedoms and also individual liberties. That certainly has not changed."

Saudi Arabia was angered after Canada demanded it "immediately release" some of the arrested activists, including Samar Badawi.

She is the sister of Raif Badawi, a prominent human rights campaigner who was sentenced to 10 years in prison in 2014 on charges of insulting Islam. His wife and children are naturalised Canadian citizens.

"Canada will always stand up for human rights in Canada and around the world, and women's rights are human rights," said Foreign Minister Chrystia Freeland on Monday.

Saudi Arabia also ordered some 15,000 of its students in Canada to leave the country. It also announced it suspended state-run airline flights to Toronto.

Nauert suggested the Canadian government could have handled the issue better.

"Some of these issues we choose to discuss privately with our friends, with our partners, with our allies," Nauert said. "I can tell you, however, we have raised these issues and I'll leave it at that."