Canadian and U.S. officials said they were concerned about the detention of a former Canadian diplomat in China, as Ottawa found itself at the center of an increasingly tense diplomatic standoff over the arrest in Vancouver of a senior executive at Huawei Technologies Co.

Michael Kovrig, a senior adviser with Brussels-based nonprofit International Crisis Group, was detained in Beijing on Monday evening by state-security officials, the group said in a statement. He recently traveled to China to work on a research report on North Korea, a person familiar with the matter said Tuesday.

It wasn’t clear whether Mr. Kovrig’s detention was related to that work. His mobile phones were switched off, and China’s foreign ministry didn’t respond to questions about his situation.

His detention comes as China and Canada wrangle over the arrest in Vancouver of Meng Wanzhou, Huawei’s chief financial officer and the daughter of its founder. She faces extradition to the U.S. on allegations she misled banks about Huawei’s business in Iran, violating U.S. sanctions. Ms. Meng denies the charges.

In Washington, State Department spokesman Robert Palladino told reporters that the U.S. was concerned about the detention of a Canadian citizen in China.