SINGAPORE - Train services on the Sengkang and Punggol LRT lines were disrupted early Tuesday morning (Oct 1) as commuters headed to work and students to school.

Public transport operator SBS Transit said services stalled at 5.40am due to a system fault.

Punggol LRT services progressively resumed from about 6.30am while Sengkang LRT services progressively resumed from about 7.35am, said Ms Tammy Tan, SBS Transit's senior vice-president for corporate communications.

SBS Transit, which operates both lines, announced in a tweet at 6.08am that both lines were down because of a system fault.

It provided free bridging and regular bus services to commuters affected by the disruption.

SBS Transit said that it notified the Singapore Examinations and Assessment Board (SEAB) of the service disruption, and no students were affected during the disruption.

Primary 6 pupils were scheduled to take the PSLE Science examination at 8.15am on Tuesday, according to the SEAB's website.

Some commuters were stuck in trains that had stopped between stations on the lines.

Safety officer Mustafa Zainudin was travelling to work when the train he was in stopped between Renjong and Sengkang LRT stations.

The 50-year-old told The Straits Times he had boarded the train at Renjong station at 5.35am, and finally alighted at Sengkang station at about 7.55am.

"The train was dark and we went for (a while) without air-conditioning," said Mr Zainudin, who took leave from work and returned home since he was late.

On the passengers being stuck in the trains, SBS Transit said that the commuters could not be allowed onto tracks and had to wait for trains to resume service for safety reasons.

"During this time, air-conditioning and lights were available on board the (trains) except for about 10 minutes when there was a cut in traction power for our staff to access the (trains)," said Ms Tan.

"We apologise to all affected commuters and are investigating the cause of the fault."