Train service from Bishan to Yio Chu Kang towards Jurong East on the North-South Line (NSL) was disrupted for nearly two hours yesterday morning.

SMRT stated on its Twitter account at about 7am that a track point fault at Ang Mo Kio MRT station delayed train service from Bishan to Yio Chu Kang by 10 minutes.

At about 8.25am, it said the delay was extended to 20 minutes.

The train operator provided free regular bus services between Bishan and Yishun MRT stations.

SMRT reported at 8.50am on Twitter the fault had been fixed and train services were progressively being restored. The free bus service stopped about 10 minutes later.

SMRT chief communications officer Margaret Teo apologised for yesterday's disruption .

She said: "At about 6am this morning, a track point fault occurred between Ang Mo Kio and Yio Chu Kang stations on the North-South Line. Services on northbound trains continued, but at a slower speed along the affected stretch as a precautionary measure. Our engineers were immediately deployed to investigate."

The fault was rectified at about 8.45am and normal train services resumed at 9am, she added.

SMRT is investigating the cause of the incident.

Commuters commented on Facebook that the disruption led to delays at other stations on the NSL during the morning rush hour.

Accounts executive Jocelyn Tan, 45, was one of the commuters caught by the train delay at Yishun MRT station.

"I waited nearly 25 minutes on the platform to get onto the train to Bishan. This side of the station was facing the hot rising sun, so it was unbearable and crammed," she said, adding that the overcrowding made people a bit paranoid due to the coronavirus situation.

The delay yesterday came after a power fault caused a six-hour disruption on the North East Line (NEL) that affected the peak-hour commute on Feb 27.

The Land Transport Authority (LTA) and NEL operator SBS Transit are investigating last week's disruption. Initial investigations found that the disruption was due to a broken contact wire that affected power supply to trains leaving the Sengkang depot.

Both incidents, only a week apart, occurred just as the MRT system has been turning in a record performance in terms of reliability.

On Feb 7, Transport Minister Khaw Boon Wan revealed that all MRT lines in Singapore have crossed the one million MKBF mark. MKBF stands for mean kilometres before failure, and is a widely used measure of reliability.

In the third quarter of last year, the Downtown and Circle lines clocked just over 900,000 MKBF, while the others - the North-South, East-West and North East lines - exceeded one million. By end-2019, all lines had crossed the million mark.

Overall, the MRT network clocked 1.32 million MKBF by December last year, a vast improvement from the 58,000 MKBF clocked in 2011.