SUBANG (The Star/Asia News Network) - A bomb hoax grounded a flight to Singapore and delayed it by about four hours at Sultan Abdul Aziz Shah airport in Subang on Tuesday (May 17).

The flight, operated by a Malaysian airline, had taken off around 7.40pm on Tuesday to Singapore when the airport's reception received two anonymous phone calls around 8pm.

Petaling Jaya OCPD Asst Comm Mohd Zani Che Din said the male caller had claimed there was a bomb on the plane.

"The air control tower was alerted to the threat and the plane was ordered to turn back.

"It made an emergency landing back at the airport around 8.20pm," he said when met at the scene on Tuesday.

A bomb squad swept the plane and no explosives were found.

The 30 passengers and four crew members were later boarded on a second plane and resumed their flight around 11.40pm.

ACP Mohd Zani said the caller spoke English in the first call and Malay in the second call shortly after.

"We are investigating the case under Section 507 of the Penal Code for criminal intimidation," he said.