In a written response to questions tabled by MPs in Parliament on Monday, Deputy Prime Minister Wong Kan Seng gave details on the initial approvals for the giant observation wheel, which halted on Dec 23 trapping 173 passengers for six hours.

Before it began operating in February last year, it had received a fire safety certificate from the Singapore Civil Defence Force (SCDF) and a temporary occupation permit from the Building Construction Authority.

As part of its application for a public entertainment licence from the police, its safety and evacuation measures also had to be certified by an independent body.

This was made up of foreign technical experts recommended by Spring, 'as there is no such expertise in Singapore,' said Mr Wong.

This approach of using an independent body to certify amusement rides is also used in Germany and the UK, he added.

The experts in this case were from the German technical services company TUV SUD and they certified it according to a 'widely used' European standard.

It covered the workmanship of the essential steel and machine components, and the operational safety performance such as the locking device on the cabin doors, normal and emergency operations, and braking mechanism.

The ministry also understands from the Flyer's management that a manual cranking device was not made part of the initial design because of the size of the wheel, said Mr Wong.

Following the incident, the Flyer is installing a separate operating system and mechanical winches. Mr Wong also gave a detailed, blow-by-blow account of the Dec 23 incident.

After an electrical fire broke out at 4.50pm damaging the main controls and the back-up equipment - 'a scenario that the Flyer management and engineers had not anticipated before' - the management then brought in engineers and alerted their rescue team.

Meanwhile, they also informed the police about the stoppage, at 5.08pm. The engineers failed to re-start the wheel, and at 7.25pm the police and SCDF were contacted. Police arrived at 7.44pm, while the SCDF arrived 10 minutes later.

By this time, the management had started evacuating passengers, so the SCDF officers went on standby at the scene.

After a second batch of passengers was evacuated, the engineers managed to restart three of the wheel's six motor units, by creating an ad hoc bypass to the control system - 'something which the engineers had not tried before.'

Mr Wong reiterated that there was no evidence of foul play, and that the police would only reissue the Flyer's public entertainment licence once a new certification report has been submitted.

He did not elaborate on whether this has been received yet.