On Monday, Ottawa expelled six Indian diplomats after the RCMP said it believes Indian agents played a role in extortion, coercion and murder.

U.S. State Department spokesman Matthew Miller says Washington takes the allegations seriously, but would not comment on the substance of the new claims or on India's decision to also expel six Canadian diplomats.

Miller says the U.S. has been asking India to co-operate with Canadian authorities for months, after the assassination of a Sikh activist near Vancouver last year.

In Ottawa, NDP Leader Jagmeet Singh is calling for any Indian diplomats involved in criminal activity in this country to face "severe sanctions."

The Liberal government is also trying to assure Canadian businesses that it wants trade with India to continue even though allegations of illegal activity caused Ottawa to suspend negotiations for a free-trade deal a year ago.

In a press conference on Tuesday, Miller did not directly criticize India's decision not to co-operate with Canadian investigations.

"As we've said before, they are serious allegations and we have wanted to see India take them seriously and co-operate with Canada's investigation. They have chosen an alternate path."

His comments come as an Indian delegation visited Washington to discuss an alleged murder-for-hire plot that U.S. officials revealed last November.

An unsealed indictment alleged an Indian government employee had directed the attempted assassination in the United States, and spoke about others, including the killing of Hardeep Singh Nijjar last June in Surrey, B.C.

Miller said the visit by what he called the Indian inquiry committee, announced on Monday, was unrelated to the allegations made public by Canadian authorities that same day.

"The statement announcing the meeting was planned early last week, maybe (the) end of the week before -- well before we were aware of the actions that Canada was going to take over the past few days. So it is completely coincidental," Miller said.

White House national security spokesman John Kirby had similar comments on Tuesday.

"I wouldn't speak for the Canadians one way or another. But we have expressed our deep concern about this to our Indian counterparts. They have expressed to us that they are taking it seriously," he said.

As the seriousness of the situation began to settle in Tuesday, Canada's Trade Minister Mary Ng moved to reassure Canadian businesses with ties to India. In a statement, Ng acknowledged the uncertainty that businesses and investors may have as a result as the diplomatic expulsions. She said the government will continue to support commercial and economic ties between the countries.

"However, we must consider our economic interests with the need to protect Canadians and uphold the rule of law," she said. "We will not tolerate any foreign government threatening, extorting or harming Canadian citizens on our soil."

Ng said the government remains "open to a dialogue" with India and looks forward to continuing a "valued relationship."

The House of Commons is not sitting this week, preventing an immediate debate on the matter, but Singh said his party will be asking the House public safety committee to study "other steps we can take to keep Canadians safe."

He called for "severe sanctions on Indian diplomats" involved in criminal activity. The RCMP in its comments Monday said there were six Indian diplomats they sought to question about the violent activities in Canada, and those six are the ones Canada expelled.

Singh said Canada must also ban a Hindu group that has been accused of hate speech by Sikh and Muslim groups.

"We are in uncharted territory, with implications for the diplomatic relationship as well as for Canada's public safety and national security," said Vina Nadjibulla, research vice-president for the Asia Pacific Foundation.

Nadjibulla said she's watching to see how Canada's peers respond to the "unprecedented, extraordinary" news. That could mean diplomatic moves behind the scenes, and possibly public statements of support for Canada.

"The reaction from the U.S. is going to be the one that everybody will be paying attention to," she said.

"In order for Canada, at this stage, to have any kind of co-operation from India and seek accountability for what has happened, we would need India to feel some pressure; we would need India to feel some reason to co-operate."

The Bloc Quebecois asked Tuesday for the government to "intensify collaboration with Canada's allies in terms of intelligence and solidarity, in the face of such acts."

The Conservatives Monday denounced Canada's "extremely concerning" allegations as proof that the government had not taken foreign interference and national security seriously.

India has insisted Canada has provided it no evidence to back up any of the allegations.

RCMP Commissioner Mike Duheme said the force's deputy commissioner tried to share evidence with Indian police last week but was rebuffed. This past weekend, deputy foreign affairs minister David Morrison, along with the RCMP, presented evidence to India in meetings held in Singapore. Canada sought India's agreement to revoke the diplomatic immunity of the six individuals but India refused.

Foreign Affairs Minister Melanie Joly said India's refusal to co-operate is why Canada declared the six diplomats persona non grata, which is one of the stiffest penalties Canada can impose under the Vienna Convention.

Nadjibulla said it was notable that Joly accused active diplomats of involvement in criminality, and that she said violence linked to the Indian government had only increased since Canada made its concerns public last year.

In September 2023, Prime Minister Justin Trudeau announced that Canadian intelligence services were investigating "credible" information about "a potential link" between India's government and Nijjar's killing.

This report by The Canadian Press was first published Oct. 15, 2024.

-- With files from Kelly Geraldine Malone