The accusation by Canada’s prime minister, Justin Trudeau, that the Indian government orchestrated a campaign to threaten and kill Sikhs on Canadian soil has cast a spotlight on the potential reach of India’s shadowy intelligence network, which has been known to operate mainly in South Asia.

Mr. Trudeau’s allegations have surprised many in diplomatic circles, who say that countries are typically reluctant to air allegations of espionage and assassinations against foreign intelligence services.

India’s neighbors — especially its archrival, Pakistan, with which it has fought multiple wars — are well acquainted with Indian covert operations, which are widely understood to have involved targeted airstrikes and assassinations on foreign soil.

But because of the public way Canada has laid out its case, the wider world is now getting a glimpse of how diplomats, spies, bureaucrats and police officers who work in Indian intelligence likely operate, and how senior government officials may direct their activities.

Mr. Trudeau’s strongly worded statements on Monday escalated a diplomatic row between the two countries that had been brewing for more than a year, over the killing of a Canadian Sikh citizen in Canada.

The Canadian authorities said on Monday that they believe six diplomats were part of a broad criminal network, spread across the country, involved in intimidation, harassment and extortion aimed at Canadian Sikhs, as well as homicides.