Canada has formally petitioned China not to follow through with the execution of a Canadian convicted of being an accessory to drug-smuggling.

鈥淲e have already spoken with China鈥檚 ambassador to Canada and requested clemency,鈥 Foreign Affairs Minister Chrystia Freeland said Tuesday at a press conference in Saint-Hyacinthe, Que.

Robert Schellenberg of Abbotsford, B.C., was sentenced to death Monday. He had previously been sentenced to 15 years in prison for the same offence, but a new trial was recently ordered.

His is the latest case in an ever-escalating diplomatic dispute between Canada and China, which began with the arrest of Chinese business executive Meng Wanzhou in Vancouver last month. Two Canadian citizens, Michael Kovrig and Michael Spavor, have since been detained in China.

Freeland said discussions were happening regularly between officials 鈥渁t a number of levels鈥 in both countries.

鈥淐ontinuing that dialogue is very important. It is a complicated and difficult moment in our relationship with China,鈥 she said.

Earlier in the day, Chinese officials accused the Canadian government of hypocrisy for updating its travel advisory to warn of 鈥渁rbitrary enforcement of local laws鈥 in China.

鈥淲e do 鈥 urge people to use a high degree of caution before travelling to China,鈥 Freeland said Tuesday.

A spokesperson for China鈥檚 foreign ministry likened Canada鈥檚 warning to a thief yelling 鈥渟top the thief,鈥 saying Canada鈥檚 arrest of Meng shows that Canada is the country where foreign nationals face greater danger.

鈥淭he Canadian government really needs to issue advice to its citizens, not for any possible danger in travelling to China, but to warn them against involving in such grave crime as drug trafficking,鈥 Hua Chunying said at a press conference, according to an from the ministry.

China also followed suit with a travel advisory of its own, warning its citizens that they should 鈥渇ully assess the risks of going to Canada for tourism鈥 and may find themselves 鈥渁rbitrarily detained at the request of a third nation鈥 in an apparent reference to Meng, who is the chief financial officer of tech behemoth Huawei.

Meng鈥檚 arrest in Vancouver, apparently in response to an extradition request from the United States government, sparked the diplomatic dispute that saw Canadian citizens Kovrig and Spavor taken into custody in China, where they have remained ever since.

Who is Robert Schellenberg?

Chinese officials have denied that Schellenberg鈥檚 retrial was politically motivated, framing it instead as part of the country鈥檚 hardline stance on drug crime.

According to the Chinese courts, Schellenberg was part of an operation to transport 222 kilograms of methamphetamine from a warehouse in China to a destination in Australia.

Although China does not publicize data around executions, it is believed that nearly 20 foreigners were put to death for offences related to drug-smuggling between 2009 and 2015. Chinese citizens found guilty of similar crimes are executed as well, Sophie Richardson of Human Rights Watch told 麻豆影视 Channel.

Schellenberg鈥檚 family said Tuesday that it wants all Canadians 鈥渢o stand with us and pray鈥 for his safe return.

鈥淭he Schellenberg family cares deeply about our Robert who is being held under very difficult circumstances in China,鈥 the family said Tuesday in a statement.

Family members had been in touch with their local MP, Conservative Ed Fast, and wanted to see the federal government 鈥渕ake every effort to secure fair treatment for Robert,鈥 the statement said.

Freeland said she had spoken to Schellenberg鈥檚 father on Monday in what she described as a 鈥渧ery emotional conversation.鈥

CTV Vancouver reports that a man with the same name and age as Schellenberg has served jail time for four drug-related convictions in B.C. in the past, three of which were for drug possession for the purpose of trafficking.

International war of words

Freeland said Tuesday that Canada considers the death penalty to be an 鈥渋nappropriate and inhumane鈥 punishment for any offence, and stressed that Canada has received support from the United States, United Kingdom, France and other countries during the dispute.

Prime Minister Justin Trudeau spoke Monday with the leaders of Argentina and New Zealand. According to the Prime Minister鈥檚 Office, the cases of Kovrig, Spavor and Schellenberg made up the bulk of the agenda in both calls.

Hua said that Trudeau should 鈥渞espect the rule of law, respect China鈥檚 judicial sovereignty, correct mistakes and stop making irresponsible remarks.鈥 She called on the Canadian government to release Meng.

Wheels are also in motion for political action on the domestic front. On Thursday the House of Commons Foreign Affairs Committee is holding in Ottawa to discuss the possibility of calling Canada's ambassador to China John McCallum to testify on the current state of China-Canada relations.

Canada and China have been working together in recent years to boost tourism activity between the two countries. Statistics Canada says more than 663,000 Chinese travellers visited Canada in the first 10 months of 2018, up from about 620,000 during the same time period in 2017.

Hua stressed that China 鈥渞emains open to and welcomes people from all countries, including from Canada,鈥 as long as they obey the law.

鈥淭he facts have proven that China is a safe place,鈥 she said, according to the translation.

Lynette Ong, a professor of political science at the University of Toronto, said any Canadians already in China should try to maintain a 鈥渓ow profile鈥 due to the ongoing tensions.

鈥淵ou do not want the government to find any excuse or any opportunities to put another Canadian in the spotlight,鈥 she said.

Human rights groups critical

Richardson, the China director of Human Rights Watch, said Tuesday that Schellenberg鈥檚 plight was attracting global attention.

鈥淚 think people around the world are horrified by this case because it鈥檚 such an incredibly crass, politicized and really grotesque response to a diplomatic spat,鈥 she told 麻豆影视 Channel.

Richardson said Human Rights Watch has long been concerned China鈥檚 justice system places defence lawyers at 鈥渘otorious disadvantages鈥 and is designed to serve political interests.

鈥淚t is a profoundly politicized system that we generally believe can鈥檛 possibly deliver on fair trial rights or real justice,鈥 she said.

Schellenberg鈥檚 sentence has also been criticized by , which said execution was not an appropriate sentence for a drug-related offence.

"China's death penalty system is shrouded in secrecy, which contributes to why many will be questioning the timing of this decision,鈥 William Nee of Amnesty International said in a statement.

鈥淲e have seen before that in highly politicized cases the trial is often a mere spectacle with the outcome already decided.鈥