A lawmaker and former MTR engineer, Gary Zhang, has called on the MTR Corporation to thoroughly review its maintenance procedures, to check if Sunday's partial train derailment at Yau Ma Tei station was caused by insufficient checking of barriers and other track installations, or loopholes in its maintenance regime.

Zhang’s comments come after an initial probe by the railway operator found that the train hit a displaced metal barrier at the station, derailing a truck on the first carriage and ripping its doors open.

Speaking on RTHK’s Hong Kong Today programme, he said that based on the preliminary information available, the partial derailment was unlikely to be because of a fault related to the train design.

“The purpose of any maintenance, the purpose of the design, is to avoid such incidents. I think the MTR should thoroughly review its maintenance regime, and really check those records to see whether the root cause is lack of maintenance, or the root cause is about some loopholes in the maintenance regime," he said.

"Whether it’s a human error, or whether it’s a loophole in the maintenance regime, like something we don’t think we need to check, but eventually something just failed. I think it still depends on the thorough investigation in the coming two months."

Last week, Zhang criticized the evacuation of some of the passengers, after 150 people exited the derailed train through an emergency door at the back and then walked along the tunnel to the next station.