OTTAWA — Four Canadians were executed in China on drug-related charges earlier this year, Canadian authorities have confirmed.

All of them were dual citizens, and their identities have been withheld upon the request of their families, Canada's foreign minister Mélanie Joly told reporters on Wednesday.

She condemned the killings as "irreversible and inconsistent with basic human dignity", adding that she had "asked personally for leniency".

A spokesperson for the Chinese embassy in Canada said evidence for the Canadian nationals' crimes was "solid and sufficient" and urged Canada to "stop making irresponsible remarks", according to reports.

The Chinese embassy also added that Beijing had "fully guaranteed the rights and interests of the Canadian nationals concerned" and urged the Canadian government to respect "China's judicial sovereignty".

China does not recognize dual citizenship and takes a tough stance on drug crimes.

Joly said she had been following the cases "very closely" for months and had tried with other officials, including former prime minister Justin Trudeau, to stop the executions.

In a statement to Canadian media, Global Affairs Canada spokesperson Charlotte MacLeod said Canada had "repeatedly called for clemency for these individuals at the senior-most levels and remains steadfast in its opposition to the use of the death penalty in all cases, everywhere".

China imposes the death penalty on serious crimes including those related to drugs, corruption and espionage. While the number of executions are kept secret, human rights groups believe China has one of the highest execution rates in the world.

However, it's rare for the death penalty to be carried out on foreigners.

The executions revealed this week have sparked criticisms from campaigners.

"These shocking and inhumane executions of Canadian citizens by Chinese authorities should be a wake-up call for Canada," said Ketty Nivyabandi from Amnesty International Canada. "We are devastated for the families of the victims, and we hold them in our hearts as they try to process the unimaginable."

"Our thoughts also go to the loved ones of Canadian citizens whom China is holding on death row or whose whereabouts in the Chinese prison system are unknown."

In 2019, Canadian national Robert Lloyd Schellenberg was sentenced to death in China for drug smuggling — in a high-profile case that drew condemnation from Canadian government. He was not among the Canadians that were executed.

"We'll continue to not only strongly condemn but also ask for leniency for other Canadians that are facing similar situations," Joly said on Wednesday.

Relations between Canada and China have been icy since 2018 after Canada detained a Chinese telecom executive, Meng Wanzhou, on a US extradition request. China arrested two Canadians shortly afterward — though all of them have now been released.

Earlier this year, Canadian media released reports, many based on leaked intelligence, about detailed claims of Chinese meddling in the country's last two federal elections. China has condemned the reports, calling them "baseless and defamatory".

More recently, China imposed retaliatory tariffs on some Canadian farm and food imports in retaliation for Ottawa's levies on Chinese electric vehicles, steel and aluminum. — BBC