THE Spanish train that hurtled off the rails killing at least 80 and smashed into a security wall was travelling at twice the speed limit, it has been claimed.

Spain's government said two inquiries had been launched into the cause of the crash on Wednesday near the northwestern city of Santiago de Compostela.

In what was Spain's deadliest train crash in four decades, 95 people remain in hospital, with 36 in critical condition, including four children.

Prime Minister Mariano Rajoy, a native of Santiago de Compostela, visited the crash scene alongside rescue workers and went to a nearby hospital to speak to those wounded and their families.

He said: "For a native of Santiago, like me, this is the saddest day."

Mr Rajoy also declared Spain would observe a three-day period of mourning.

Spain's head of state, King Carlos, and Queen Sofia went to the same hospital, dressed in black.

Witness accounts backed by security-camera footage of the moment of disaster suggested the eight-carriage train was going too fast as it took a left bend underneath a road bridge.

The train company Renfe said 218 passengers and five crew members were on board.

Spanish officials said the speed limit on that section of track is 50mph. But an estimate of the train's speed at the moment of impact, using the time stamp of the video and the estimated distance between two pylons, gives a range of 89-119mph.

Another estimate calculated on the basis of the distance between railroad ties gives a range of 96-112mph.

The video footage, which the Spanish railway authority Adif said probably came from one of its cameras, shows the train carriages start to buckle soon into the turn.

Experts say it appeared a diesel-powered unit behind the lead locomotive was the first to derail. The front engine itself quickly followed, violently tipping on to its right side as it crashes into a concrete security wall and bulldozes along the ground.

In the background, all the rear carriages can be seen starting to decouple and come off the tracks.

The picture goes blank as the engine appears to crash directly into the camera.

After impact, witnesses said a fire engulfed passengers trapped in at least one carriage.

Police plan to question the 52-year-old train driver, who is hospital with unspecified injuries, as both a witness and as a possible suspect.

However, officials said possible faults in safety equipment were also being investigated.

Santiago officials had been preparing for the city's celebrated Catholic festival but cancelled it and took control of the city's main indoor sports arena to use as a makeshift morgue.

There, relatives of the dead could be seen sobbing and embracing each other.

CCTV footage shows the moment Spanish train left the track

CCTV footage shows the moment Spanish train left the tracks