A Canadian national was arrested in Chiang Mai after opening an emergency door on a Thai Airways International (THAI) flight bound for Bangkok, triggering the emergency evacuation slide.

The incident happened as the plane was taxiing to the runway for takeoff at Chiang Mai airport on Wednesday night.

According to witnesses, just moments before the 9.05pm departure, the 40-year-old man, whose name was withheld, rushed to open a front emergency door, automatically triggering the emergency slide. 

The Chiang Mai to Bangkok flight stopped. Another passenger and flight attendants successfully subdued the man, who allegedly said that he believed someone was about to attack him.

Passengers had to return to the airport terminal, where they later boarded another plane. The flight departed at 12.34am.

THAI technicians had to cut off the slide.

The blocked runway was reopened at 10.50pm on Wednesday.

The incident affected 2,296 passengers across 13 flights comprising three outgoing flights, eight incoming planes that had to circle around the airport and two flights that were diverted to other airports.