After searching the plane and the baggage of the person that made the threat and his two travelling companions, police said no such threat was found.
Three passengers were assisting police with their investigations, they said, adding one of them, a 41-year-old man, had been arrested for making a false bomb threat.
Scoot, the budget carrier of Singapore Airlines, said that all 173 passengers and six crew aboard the Airbus A320 were safe and that the flight TR634 would resume its journey to Hat Yai in the evening.
Singapore has a near-perfect record of keeping its shores free of terror, but it has markedly stepped up efforts to deter militancy in recent years with more frequent attacks on Western countries and after Islamic State militants briefly took over a town in the southern Philippines last year.
"For our RSAF pilots who are on stand-by duties 24/7, every threat is considered real until proven otherwise," said Ng Eng Hen.
A Scoot staff member at the airline's check-in desk at Changi told Reuters that the incident had caused some delays to flights which had since been cleared up.
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