French company Thales - whose rail signalling system was blamed for a Monday morning collision of two trains during a trial run in Hong Kong - has begun investigations into the incident and is expected to submit a preliminary report to the city's rail operator MTR Corp on Friday.
The safety of the Thales system had come under the spotlight as the company's system was linked to another train collision in Singapore in 2017 - even though both Thales and the Singapore authorities have said that the two accidents were different.
Mr Amaury Jourdan, chief technical officer for transportation activities at Thales, said the company would assist MTR in the matter as much as possible.
The company's experts have arrived in the city to help with investigations into the incident.
Speaking on the sidelines of the Asia Pacific Rail conference in Hong Kong, he added that the signalling system used in every city is customised and different.
Thales, in a joint venture with fellow French company Alstom, was awarded in 2015 a €330 million (S$506 million) contract to upgrade MTR's signalling system.
The upgrade is now expected to be delayed. The new system was to be rolled out in the later half of this year.
MTR outgoing chairman Frederick Ma said yesterday that the firm "reserves the right to pursue the matter" with Thales and Alstom.
Local news outlet HK01 yesterday cited that a government source had ruled out human error as the cause of the crash - the first such accident in 40 years of MTR operations in Hong Kong.
On Monday, MTR said that a software glitch resulted in a signalling fault that led to the collision on the Tsuen Wan line in which a driver was hurt.
The same day, MTR's managing director Jacob Kam Chak-pui said Thales had identified a similar problem in a computer simulation in its Toronto laboratory. That laboratory in Canada has been tasked with piecing together Monday's events.
And while the chaos triggered by the rail disruption may have calmed yesterday, public confidence in MTR appears to have been shaken after this episode.
Mr Isaac Mo, 28, said he is "very disappointed" with the MTR. "We don't even understand why MTR has had so many errors, delays or accidents in recent months. The management and quality of MTR have declined... I think the government has a responsibility to monitor how MTR performs and why the issues persist."
Another commuter King Leung, 35, said: "This should have been caught during a software simulation, not at a hardware testing environment.
"It seems like they were close to deploying, and it is worrying."
But commuter Sandeep Hathiramani, 31, said the silver lining was that the casualty was minor and the signalling system "will get a good review before roll-out".
Hong Kong Chief Executive Carrie Lam yesterday pledged: "I would like to reiterate public safety is of primary concern. So, we will not rush to open the Sha Tin-Central link or put in place this new signal system until we are assured of their safety."
The new Sha Tin-Central rail link around Hung Hom station, costing HK$97.1 billion (S$16.7 billion), is the city's most expensive rail project, but it has been plagued by allegations of shoddy work. It is expected to use the new signal system too. Services between Central and Admiralty stations on the Tsuen Wan line remained suspended yesterday.
MTR operations director Adi Lau Tin-shing said the nature of the accident and the damage done to the trains made removal of the train and repair works complicated.
He said it was difficult to set a timeline as to when services between the two stations on Tsuen Wan line will resume, but the company is trying its best to solve the problem.