SINGAPORE - A person who is said to have found his way twice onto the MRT train tracks between the Bukit Gombak and Yew Tee stations on Friday night caused delays and halted services between both stations.

An SMRT spokesman told The Straits Times that delays along the North-South line around 9pm were due to a "track intrusion", meaning a person had been found on the tracks.

Earlier at 8.45pm, a member of the public reported to the police that a man was seen walking on the viaduct - the tracks above ground - between Choa Chu Kang and Bukit Gombak MRT stations.

"As a safety precaution, SMRT staff proceeded to immediately stop train services to investigate the alleged track intrusion," read a Facebook post on SMRT's official page.

Free bus services and bus bridging between Jurong East and Yew Tee were activated by about 9.15pm, and by 9.32pm, normal train services had resumed.

But minutes later at about 9.45pm, SMRT tweeted that the train service between Bukit Gombak and Yew Tee in both directions had been halted as "the person intrudes to the track again".

It took almost an hour before train services resumed at about 10.35pm, and the night's disrupted services affected many commuters who took to social media to complain about the crowds stranded at stations.

It is the second major incident this week - train services were disrupted for more than four hours on Monday.