SINGAPORE - Service on the Circle Line continues to be slow on Tuesday (Aug 30), as the signalling fault that disrupted service on Monday persists, said rail operator SMRT.

Those travelling on the Circle Line should expect up to five minutes of additional travelling time for the rest of the day, it said in a statement on Tuesday.

Commuters had complained of delays and stalled trains on the Circle Line during their morning travel on Tuesday.

The Circle Line delay took place at the same time as a three-hour disruption on the North-South Line, which SMRT later attributed to a fault with track-side signalling equipment near Choa Chu Kang MRT station.

Circle Line train speeds and service frequency first took a hit during morning rush hour on Monday, when commuters complained of packed stations and poor communication about the problem.

It was not until Monday afternoon that SMRT announced that unspecified "intermittent signalling issues" were to blame.

SMRT has been carrying out tests and investigations ever since, said SMRT vice-president for corporate information and communications Patrick Nathan, but the issue has not yet been resolved.

He added that SMRT is working with the Land Transport Authority and the contractor to address the problem, which has since been identified as a fault in wireless communication between signalling equipment on the train and on the track.