The governments of the United States and the United Kingdom are calling on the Indian government to reverse its efforts to reduce the presence of Canadian diplomats in the country and to "adhere" to its obligations under international law.

The Canadian government announced on Thursday that it had withdrawn 41 of its 62 diplomats from India after New Delhi issued a request for diplomatic parity between the two countries by October 10.

Foreign Minister Mélanie Joly, in her "unreasonable" request for diplomatic parity, stated that India would allow only 21 Canadian diplomats and their families to maintain their diplomatic status in that country, leaving the others stripped of diplomatic immunity and vulnerable to retaliation or arrest.

Officials from the United States and the United Kingdom expressed their concerns about the recent developments on Friday.

U.S. State Department spokesperson Matthew Miller said in a statement released on Friday: "We are concerned about the departure of Canadian diplomats from India in response to the Indian government's request for Canada to significantly reduce its diplomatic presence in India."

He added, "Resolving disputes requires having diplomats on the ground; we have urged the Indian government not to insist on reducing Canada's diplomatic presence and to cooperate with the ongoing Canadian investigation."

Miller stated that the United States expects India to "meet its commitments" under the 1961 Vienna Convention on Diplomatic Relations, "including regarding the privileges and immunities enjoyed by accredited members of the Canadian diplomatic mission."

The UK's Foreign, Commonwealth & Development Office (FCDO) expressed similar concerns, stating that it "disagrees with the decisions made by the Indian government" that led to the departure of several Canadian diplomats from India.

A spokesperson for the Foreign Office said in a statement released on Friday: "We expect all countries to meet their obligations under the 1961 Vienna Convention on Diplomatic Relations."

"The unilateral cancellation of privileges and immunities that ensure the safety and security of diplomats is inconsistent with the principles of the Vienna Convention or its effectiveness."

Joly also accused India of acting "in violation of international law" and breaching the Vienna Convention on Diplomatic Relations.

Prime Minister Justin Trudeau said on Friday in Brampton, Ontario: "They are choosing to violate a very fundamental principle of international law and diplomacy," adding, "This is something that all countries of the world should be deeply concerned about."

On the other hand, the Indian government rejected accusations that it violated international law when it requested Canada to withdraw its diplomats to achieve roughly equal numbers of staff in each country.

The Indian Ministry of External Affairs stated in a release on Friday: "We reject any attempt to portray the application of parity as a violation of international norms."

These comments come in the wake of a diplomatic dispute between India and Canada, which crystallized last month when Trudeau accused the Indian government of having a role in the murder of prominent Canadian Sikh leader Hardeep Singh Nijjar in June in British Columbia.

At the time, Trudeau stated that intelligence agencies were investigating "reliable allegations" regarding Nijjar's death on Canadian soil, a claim vehemently denied by India.

Joly and Trudeau indicated that federal law enforcement agencies in Canada are "actively" investigating the murder, and officials have urged India to cooperate.

David Cohen, the U.S. Ambassador to Canada, previously told CTV News that there is "shared intelligence among Five Eyes partners" that informed Trudeau's public claim about India's involvement in the Sikh separatist leader's death.

Cohen added that there have been "many communications between Canada and the United States on this matter," without going into detail.