An official inquiry on Monday urged that all Lisbon cable cars remain suspended for urgent safety modifications following a deadly September crash blamed on a faulty cable.

The Sept. 3 crash when the funicular came off the rails and hurtled into a building left 16 dead. The official inquiry's preliminary report said Lisbon's cable cars cannot resume operating until they can guarantee they have braking systems "capable of immobilizing the cabins in the event of a cable break."

According to the investigators' initial findings, the funicular was going at a speed of 60 kilometers (37 miles) an hour before it crashed. The whole incident happened in just 50 seconds, they added.

Eleven of the 16 victims were foreign nationals, with three U.K. citizens, two South Koreans, two Canadians, one Frenchwoman, one Swiss, one American, and one Ukrainian identified among the dead.

The crash also injured some 20 people, including at least 11 foreigners.

The Portuguese victims included four members of staff from the same social care institution, whose offices sit at the top of the sheer side road serviced by the funicular.

'Time bomb'

First opening in 1885, the Gloria's two wagons have been propelled up the steep hill by a system of counterweights across its 265-meter (870 feet) track, up and down a 48-metre incline.

Investigators said that a routine inspection on the morning of the accident found nothing unusual about the cable that snapped.

But Carlos Neves, who heads the mechanical engineering college of Portugal's engineering regulator, told AFP that the points where the cable latches onto the cabins would only be visible when they are replaced every two years.

According to the GPIAAF's note, the Gloria's driver had activated the funicular's brakes, but those were unable to halt the carriage without the counterweight system's help.

"It's structural security flaw," said Neves, comparing it to "a time bomb."

"How is it possible that a public transport system did not have an effective security system? In my opinion, that's the big question that needs answering," the engineer added.

In the wake of the Gloria's derailment Lisbon's other funiculars have remained closed while investigators assess their safety.