Two Singapore fighter jets escorted a civilian plane bound for Thailand safely back to the city-state on Thursday after a bomb threat by a passenger that
turned out to be a false alarm.

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.

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.

Singapore's defence minister said in a Facebook post that two F-15SG fighter jets had immediately responded to the threat when alerted by the pilot and escorted the plane from the South China Sea back to Changi airport.

"For our RSAF pilots who are on standby 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.

--Reuters