Saudi Arabia and Canada showed no signs of backing down in an escalating row over human rights, after Riyadh abmptly cut ties over Ottawa's vigorous calls for the release of activists jailed in the kingdom.

The Saudi government expelled Canada's ambassador, giving him 24 hours to leave the country, and recalled its own envoy to Ottawa, while freezing all new trade over what it slammed as "interference" in its internal affairs.

Ottawa did not give any ground over the shock expulsion of the envoy, Dennis Horak, with Foreign Minister Chrystia Freeland saying Canada would continue to defend human rights around the world.

The mpture, which underscores a newly aggressive foreign policy led by Crown Prince Mohammed bin Salman, comes after Canada denounced a new crackdown on women and human rights campaigners in the kingdom.

Saudi Arabia also announced "the freezing of all new trade and investment transactions with Canada while retaining its right

to take further action ”.

Later Monday, the row appeared to escalate as Riyadh said it will relocate thousands of Saudi students studying in Canada to other countries, and state airline Saudia announced it was suspending flights to and fromToronto.

Last week, Canada said it was "gravely concerned" over the new wave of arrests of rights campaigners, including awardwinning gender rights activist Samar Badawi, and called on Riyadh to "immediately release them."

Canada doubled down on Monday.

"Canada will always stand up for human rights, in Canada and around the world," Freeland told an audience in Vancouver.

“It is now time for other governments to join Canada in increasing the pressure on Saudi Arabia to release all prisoners of conscience immediately and unconditionally," said Samah Hadid, Amnesty International's Middle East campaigns director. But Riyadh's singling out of Canada is aimed at strongly discouraging other critical Western governments from speaking out, observers say.