Two high-speed ​trains collided in Spain just after 9am (0800 GMT) on Wednesday, leaving at least 68 killed.

The line connecting Madrid to the southern Andalusia region has been suspended.

It is feared the death toll may climb higher.

Spain's transport minister saying a Renfe train had been authorised to continue its journey despite a red signal due to the stationary train ahead.

Oscar Puente told reporters in Madrid that the red signal was issued due to a computer communications failure, which automatically stopped traffic, and an erroneous decision had been made to restart the Renfe train, in a breach of protocol.

Ambulances, funeral home vans and helicopters were parked next to one of the trains on an elevated section of track, while twisted metal, broken panels and wreckage were strewn across an embankment down which at least three carriages had plunged.

Twisted metal, broken panels and wreckage were strewn across an embankment down which at least three carriages had plunged.

"It's like I was flying from my seat," said Frederic Barrileia, a tourist from the Philippines, describing the impact of the crash.

Another survivor, Salvador Arriaza, said seats were ripped out and people flung into the air in his carriage. He saw some people trapped under seats, while others broke windows to escape.

This is the second major deadly train crash this year, after an accident in January between high-speed trains belonging to the same operators on the same line killed 46 people

The crash comes at a politically sensitive time for Spanish Prime Minister Pedro Sánchez who called a snap election for November 29.