The cable that snapped on the Lisbon funicular was not up to the standards laid out by the city's transport operator, according to a preliminary report released Monday.

The crash in September killed at least 16 people and injured 21 others after one of the carriages on the railway derailed and crashed into a building in central Lisbon.

The Gloria funicular, classified as a Portuguese national monument, is one of the four in the city and is hugely popular with tourists for its short trip on a steep street in central Lisbon.

It has two carriages traveling in opposite directions.

In the deadly incident in September, the cable connecting the two carriages snapped, with the top car hurtling down the hill at high speed. 

What did the report say?

In its 35-page preliminary report, the Office for Air and Rail Accident Prevention and Investigation (GPIAAF) said that the underground steel haulage cable that connected the two cars wasn't strong enough.

"The cable did not comply with the specifications in force at the CCFL to be used for the Gloria tram," the report said, with the acronym referring to the city's transport operator.

The other funiculars in the city have been suspended since the crash. The investigating body said that inspectors have yet to confirm that braking systems "capable of immobilizing the cabins in the event of a cable break" are operable.

In the case of the Gloria funicular, the cable had been in use for less than a year. 

The investigation identified five instances when the maintenance program referred to "non-existent, inapplicable or outdated standards," the report said.

After the cable broke, safety systems cut power to the funicular, meaning that the pneumatic brake no longer worked and the manual brake wasn't strong enough to stop the car hurtling down the hill.

A complete analysis of the deadly accident is expected next year.

Edited by: Karl Sexton