The delays started at 6am today.
SMRT issued a warning at 7.26am saying that an “intermittent power fault” was causing trains on both lines to run at longer intervals.
The cause of the disruption was a loose door in the tunnel near Tiong Bahru MRT station which caused power trips.
At 11.30am, train service was shut down between Queenstown and Bugis stations for 30 minutes for “urgent repair works”.
Normal train service on the North-South Line resumed at about 10.20am, while the track circuit fault at Commonwealth was rectified at about 11am.
At 2pm, more than seven hours after delays first began, SMRT said train service on the East-West Line was back to normal.