Media outlets in Taiwan say Vice President-elect Hsiao Bi-khim was followed by a Chinese military diplomat in the Czech capital Prague.
Hsiao will become Taiwan's next vice president in May and visited the Czech Republic in March.
An official of a Czech think tank posted local media reports about the incident on social media.
Based on these reports, several Taiwanese media outlets said on Saturday that Hsiao's motorcade was followed by a car from Prague airport to the city center.
They said the suspicious car ran a red light at an intersection, almost causing an accident.
Police officers stopped the car and discovered it was driven by a diplomat from the military section of the Chinese Embassy in Prague.
Taiwan's foreign ministry said it made inquiries with Czech authorities who have opened an investigation.
The Vice President-elect had served as Taiwan's representative in the United States until November 2023.
Chinese authorities believe that in August 2022, Hsiao facilitated the visit to Taiwan by then US House Speaker Nancy Pelosi, and imposed sanctions on her.