India has stopped issuing visas to Canadian citizens amid an escalating row over the killing of a Sikh separatist on Canadian soil.
India said the temporary move was due to "security threats" disrupting work at its missions in Canada. Canada's visa services remain open in India.
Tensions flared this week after Canada's leader said India may have been involved in the 18 June killing.
India angrily rejected the allegation calling it "absurd".
Relations between the countries - key trade and security partners, and US allies - have been strained for months. Analysts say they are now at an all-time low.
India's government swiftly made clear the suspension of visa services also "applies to Canadians in a third country".
"There have been threats made to our high commission [embassy] and consulates in Canada," a foreign affairs ministry spokesman in Delhi said. "This has disrupted their normal functioning. Accordingly [they] are temporarily unable to process visa applications."
He said: "India is looking for parity in rank and diplomatic strength between the diplomatic missions of the two countries. This is being sought because of Canadian diplomatic interference in our internal affairs."
Hours earlier Canada had announced it was reducing its personnel in India, saying some diplomats had received threats on social media.
"In light of the current environment where tensions have heightened, we are taking action to ensure the safety of our diplomats," a statement said.
The two countries have historic close ties - and much is at stake.