Prime Minister Justin Trudeau’s appeal to the U.S. to help secure the release of two Canadians detained by Chinese authorities is “a waste of time,” China’s foreign ministry said Friday.

Ministry spokesman Geng Shuang delivered the remarks at a media briefing one day after Trudeau urged Washington to delay finalizing a trade deal with China until Michael Kovrig and Michael Spavor have been released.

“I wonder if Canada feels too bitter to cry now,” Geng told reporters. “If you pull chestnuts out of the fire for others, you will end up being the one getting burned.”

Trudeau told the private French-language television channel TVA on Thursday that his government asked the Trump administration to delay the signing of a final trade agreement with China until Beijing hands back Kovrig and Spavor.

Kovrig, who took a leave of absence from Global Affairs Canada to work as the North East Asia analyst for the non-governmental think tank International Crisis Group, and Spavor, a China-based Canadian entrepreneur, were detained by Chinese authorities on Dec. 10, 2018 on charges of “endangering national security.”

Their arrests came days after Canadian officials arrested Meng Wanzhou, chief financial officer of telecom giant Huawei, at the request of U.S. authorities.

Meng, who is also the daughter of company founder Ren Zhengfei, is fighting extradition to the United States over allegations she was involved in violating sanctions on Iran.

The arrests triggered a bruising diplomatic crisis between Beijing and Ottawa, which found itself caught between two giants.

Attempts to pressure China by ganging up or creating links with other issues won’t work. @CanadaFP pic.twitter.com/gI4xIc3oL8 — Spokesperson发言人办公室 (@MFA_China) December 20, 2019

“Canada is entirely responsible for current difficulties in China-Canada relations,” Geng said. “Whoever started the trouble should end it. We urge Canada to take China’s solemn position and concerns seriously, correct its mistake, and immediately release Ms. Meng Wanzhou back to China.”

The U.S. and China agreed on the first phase of a trade deal on Dec. 13, which will see lower U.S. tariffs on Chinese goods and higher Chinese purchases of U.S. farm, energy and manufactured goods.

Beijing and Washington are also set to start working on the second phase of the trade deal, which would focus on a key U.S. complaint that China effectively steals U.S. intellectual property by forcing U.S. companies to transfer their technology to Chinese rivals.

Chinese authorities did not appreciate Trudeau’s attempt to tie the fate of the trade deal to the issue of detained Canadians.

“Here’s some advice to the Canadian side: don’t waste your time and effort on ganging up on China or pressuring China for unrelated matters, because you will gain nothing from that,” Geng said.

When asked whether the U.S. had made any appeals for Kovrig and Spavor’s release, Geng evaded the question.

“We have said many times before, reaching Phase One serves the interests of China, U.S. and the world,” he said.

Last week, Chinese authorities announced that after nearly a year in detention the cases of Kovrig and Spavor will transferred to the prosecutors.

“Michael Kovrig’s case involves covertly gathering state secrets and intelligence for foreign forces, and Michael Spavor’s involves stealing and illegally providing state secrets to foreign forces,” Chinese foreign ministry spokesperson Hua Chunying told reporters on Dec. 10.

The two men, who are being held separately, haven’t been allowed any contact with the outside world except for monthly consular visits by Canadian officials.

With files from CBC News and Reuters