SINGAPORE - Grease found on the tracks caused trains to travel at a slower speed along the North-South Line on Monday morning (Oct 8).

Reports of slower train service along the line began circulating online at around 7am.

Some commuters said that stations between Sembawang and Ang Mo Kio were affected, while others claimed that they had been experiencing slower train service at stations as far as Woodlands.

In response to queries from The Straits Times, Ms Margaret Teo, vice-president of corporate communications at SMRT, said that grease had been found on the train tracks in the morning.

As a precautionary measure, commencement of train service between Sembawang and Ang Mo Kio in both directions was delayed until 5.40am.

Ms Teo said that announcements were made in stations and on trains, and that free bus services were made available.

She added: "Train services commenced, albeit at a slower speed, at about 5.40am when it was determined that the grease would not cause slippage.

"The grease on the track has since been cleaned up. An investigation is ongoing to determine the cause of the incident."