The Chinese-Japanese consortium which built the 26 MRT trains that developed hairline cracks had the highest quality score among those who tendered for subsequent contracts, said the Land Transport Authority (LTA) yesterday.

Responding to queries on why it continued to award contracts worth more than $800 million to Kawasaki-Sifang after cracks were found in the first batch of trains, LTA said it "looked at the overall quality that the contractor can deliver".

"We also considered that the contractor was able to quickly identify the cause of the defects, take responsibility and carry out the necessary action promptly to rectify the fault," said a spokesman.

She said the quality score is based on different aspects such as technical proposals, project management and train manufacturer competency.

Kawasaki Heavy Industries also had a proven track record, having provided the first set of trains for the North-South and East-West lines, she said.

LTA also refuted online reports stating that Kawasaki-Sifang had used fake test records.

"Works at the factory are not just supervised by the contractor's staff, but also LTA personnel from Singapore," she said. A series of rigorous tests are then carried out before any train is accepted.

On a report on Hong Kong's FactWire website that "thousands of brackets" were added as a temporary measure to keep the trains safe from the cracks, LTA said this was inaccurate.

"The hairline cracks are on the surface of the car-body bolster which is fixed to the train car body and did not affect the structural integrity of the train. We did not add brackets at any time to the underframe."