SINGAPORE - The Land Transport Authority is investigating Wednesday's 7-hour disruption on the Downtown Line - the longest on Singapore's newest MRT line.

Meanwhile, one door remains inoperable on Thursday, some 30 hours after the malfunction was detected.

The incident, which affected at least 10,000 commuters between start of service and lunch time, was traced to faulty doors at the Botanic Gardens station.

Meanwhile, the Ministry of Education is checking if any students were late for examinations as a result of the incident.

The malfunctioning doors, believed to have been caused by a short circuit, were the third door-related fault on the Downtown Line in the past seven months.

The doors were supplied by Faiveley Transport of France, which refused to comment on the repeated incidents regarding its doors.