Open this photo in gallery In this file image made from video taken on March 2, 2017, Michael Spavor, director of Paektu Cultural Exchange, talks during a Skype interview in Yanji, China. The Associated Press

A fundraiser for a Canadian man detained in China has been deleted by a United States internet firm, leaving organizers of the charitable effort in the dark.

Donors had already committed more than $14,000 for Michael Spavor’s benefit when GoFundMe pulled the campaign, which was started in mid-December.

People who donated said they received an e-mail early Saturday saying their money had been refunded, resetting the tally of funds raised to almost zero. But GoFundMe continued to accept contributions.

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Less than 24 hours later, the campaign vanished without warning. GoFundMe sent less than $500 in donations to Mr. Spavor’s brother, the designated beneficiary.

Friends of Mr. Spavor organized the fundraiser. He was detained Dec. 10 in China, where he and former Canadian diplomat Michael Kovrig have been accused of endangering national security. Both men are being held without charges while China demands the release of Meng Wanzhou, the chief financial officer of Huawei. The United States has sought the extradition of Ms. Meng to face fraud charges related to the violation of sanctions against Iran.

A fluent Korean speaker, Mr. Spavor has worked in China for many years, arranging trips to North Korea for tourists, investors and athletes, including Canadian hockey players and former NBA star Dennis Rodman. China is the point of departure for trips into the isolated country, and friends of Mr. Spavor worry that, even if he is released, his detention will make it impossible for him to continue that business.

The fundraiser was intended “to help with any legal, medical or transportation bills once he’s out,” according to the listing.

GoFundMe did not respond to multiple requests for comment, nor did it provide a clear explanation to fundraiser organizers for its cancellation of the campaign.

But the fundraiser description mentioned that “Michael ran a small organisation that promoted exchanges with North Korea.” Andray Abrahamian, a friend of Mr. Spavor and an organizer of the fundraiser, said it’s possible Mr. Spavor’s connections to that country caused GoFundMe to pull the campaign even though the designated beneficiary for the fundraiser lives in Canada.

“U.S. sanctions are such that any financial institution that catches a whiff of North Korea goes running,” he said. “The risks are just so high now for them.”

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The international community has imposed a regime of harsh sanctions against North Korea that specifically targets the provision of “financial, material, or technological support” to sanctioned entities. U.S. authorities have taken action against at least one Russian bank for working with North Korea, and have directly warned South Korean banks to comply with international sanctions, after several institutions said they were hoping to resume work with North Korea amid warming relations between Seoul and Pyongyang.

Virtually all Western banks have, however, refused to allow any transactions related to North Korea.

Organizers of the GoFundMe campaign said they hope to launch another fundraiser.

But “now we are looking like having to start the whole thing again, minus some of the early momentum and Christmas generosity,” said Jacco Zwetsloot, a friend of Mr. Spavor and one of the organizers. “I’d be surprised if we can reach the same amount.”

Andrei Lankov, a professor at Kookmin University in Seoul who is an authority on North Korea, was among those who donated to the GoFundMe campaign.

“Michael is my friend, and he was caught in the crossfire, essentially becoming a hostage in a conflict between China and U.S. Once he is released, his small business is likely to be ruined, so he will need to restart his life from the scratch," he said. “Donations will help to mitigate his problems. This is important, since Michael was essentially the proverbial ‘innocent bystander.’”