Beijing’s detention of a former Canadian diplomat is being seen by friends and former colleagues as payback for Canada’s arrest of a well-connected Chinese telecommunications executive at the behest of the U.S., potentially escalating diplomatic tensions already roiling the global economy.

Michael Kovrig spent years in China exploring sensitive issues, delving into Beijing’s suppression of Muslims and its ties to North Korea, from his posts as a Canadian diplomat and, most recently, as a researcher for a crisis-monitoring group.

Chinese state-security agents detained Mr. Kovrig in Beijing on Monday, his employer, the International Crisis Group, said. In the aftermath, diplomats and friends are asking whether he is being punished for his work or used as a pawn over Canada’s arrest of Meng Wanzhou, the chief financial officer of Huawei Technologies Co. and the daughter of its founder.

“If Michael’s detention was intended to send a message to the Canadian government, it has been a serious political miscalculation,” said Jude Blanchette, a China analyst at U.S. advisory firm Crumpton Group, who has known Mr. Kovrig for several years. “The message it sends to businesses around the world is that they need to think twice about sending executives to China.”

Canadian officials said Wednesday that they are trying to locate a second Canadian in China who had been questioned by Chinese authorities, and later identified the individual as Michael Spavor. Mr. Spavor, 43 years old, has led academic, tourist and business delegations on visits to North Korea through his nonprofit, Paektu Cultural Exchange. Along the way, he has befriended Dennis Rodman, the retired American basketball player, and with him traveled to Pyongyang and met North Korean leader Kim Jong Un.