SINGAPORE - South-bound train service on the North-South Line (NSL) was crippled for close to half an hour early Tuesday (April 26) morning - the third time in less than a week that Singapore's oldest MRT line has suffered a disruption.

NSL operator SMRT said in a tweet at 6.31am that there was no service from Woodlands to Kranji stations, and advised commuters to seek alternative transport.

It said in a subsequent tweet that the breakdown was due to a traction power fault, while free public and shuttle buses were activated at affected stations.

Normal service resumed about 18 minutes later at around 6.49am, according to SMRT.

In its latest update at 7.20am, SMRT said some trains and stations were still crowded due to congestion.

In a statement on Facebook, SMRT apologised to commuters and said it was investigating the cause to determine if it was related to the disruption on Monday (April 25) evening.

Tuesday morning's disruption comes less than 12 hours after a power dip caused an unprecedented breakdown of train services along three MRT lines and one LRT line, as the journeys of thousands of commuters were affected towards the end of the evening peak hour.

Along the NSL, stations from Jurong East to Kranji were hit.

Last Thursday, a stalled engineering train at Raffles Place station knocked out a stretch of the line from Marine South Pier to Newton for almost an hour.