SINGAPORE - The Land Transport Authority (LTA) has asked transport provider SMRT to do a systemwide check on all service maintenance doors, after a loose door was found to be the cause of multiple delays along the North-South and East-West lines on Tuesday (July 25) morning.

In a statement, the authority said that "the cause of the power trip was traced to a loosened service maintenance door next to the tracks in the tunnel near Tiong Bahru MRT station along the EWL".

In order for engineers to safely access the tracks to remove the door, train services between Queenstown and Bugis stations stopped for 30 minutes as traction power had to be switched off.

The door was removed by noon and normal train service progressively resumed.

Added LTA: "As a precautionary measure, the LTA has asked SMRT to do a systemwide check on all the service maintenance doors. We are investigating the cause of the loosened door to prevent it from recurring."

Service maintenance doors are used by maintenance staff to access train tunnels, and are not for commuter use.

The transport authority added that the incident is not related to the ongoing tests of the new signalling system on the North-South Line, which had been the cause of several delays in recent months.

The delays on Tuesday morning (July 25) started as early as 6.30am, with several commuters claiming that they were stuck at Lakeside MRT station.

In a tweet at 7.26am, SMRT said trains were running at longer intervals because of an "intermittent power fault".

The East-West Line was also hit by a track circuit fault at Commonwealth station later in the morning, with SMRT tweeting at 8.51am to warn of delays of up to 15 minutes for commuters travelling from Joo Koon to Commonwealth stations. It subsequently revised the estimate to 20 minutes at 9.33am.

Later at 11.15am, it said on Facebook that "a loose panel" near Tiong Bahru MRT station caused the North-South and East-West lines to experience "intermittent traction power tripping".

At about 11.55am, a large crowd was seen at one of the bus stops at Queenstown MRT station, with commuters looking to other forms of transport to continue their journey.

At City Hall MRT station, Ms Giselle Chong, 24, a financial planner, waited for 45 minutes for alternative transport to get from City Hall to Bugis.

She did not know that the train service was back up at about noon and was still waiting for a cab to get from City Hall to Bugis at 12.05pm.

"I was supposed to be early for my appointment at 12.30pm, but I guess I can still make it now since the disruption wasn't too long," said Ms Chong, who boarded the train at 12.10pm.