The MTR Corporation said a preliminary investigation found that a fault in the coupling between two carriages led to the breakdown of a train on the Tseung Kwan O line on Monday.

The railway firm said at a media briefing on Thursday that after a thorough inspection, it’s found a faulty part in the coupler between the sixth and seventh carriage, which triggered the safety system and stopped the train.

The company’s Operations Director, Tony Lee, said the manufacturer of the component has sent representatives to Hong Kong to help with the probe, adding that an initial report has been submitted to the government.

“Based on the preliminary investigation, we identified that at the time of the incident, the fail-safe protection system was triggered and stopped the train,” he said.

“The gangway was found extended because an energy-absorption device inside the coupler was loosened. The gangway at the time, including the coupler, remained intact, and in connection state.”

He did not comment when asked whether human error was involved.

Penalties and compensation will be decided in accordance with its agreement with the government, Lee added.

He reassured members of the public that the MTRC has the capability to take up more railway construction projects.