Reported by BBC World
Leaked audio recordings that were published in Spanish media have revealed conversations between train drivers and a control centre just minutes before a deadly crash on Wednesday morning, that has killed 69 people.
Officials are investigating the cause of the disaster, which occurred when a train from Madrid to Seville barrelled into a stationary train.
Three audio recordings between Madrid's control centre and two train drivers appear to show that one high-speed train was given clearance to move even though another train had stalled on the track, about 25km (15 miles) ahead.
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Prime Minister Pedro Sánchez has said that authorities will "get to the bottom of every last detail of this tragedy".
Dozens of people were injured, with survivors recounting harrowing scenes people crying and bleeding, passengers trapped in their seats, missing limbs and smoke billowing throughout the carriages, one of which caught fire.
On Thursday, Spain's King Felipe VI and Queen Letizia visited some of the injured passengers in a hospital in Toledo.
He later expressed condolences to the victims' relatives, pledging that the investigation would determine why the crash happened, and what measures would be taken for this not to happen again.
The crash is one of the worst rail disasters in Europe's modern history, and Spain's worst crash since 2013. On Thursday, the country began three days of national mourning.
The moving train, run by state-owned operator Renfe, had 397 passengers on board. The stationary train was run by private operator Iryo, and carrying 147 passengers.
A reported issue with the automatic signalling system - a computer failure - had forced all trains to halt on the affected stretch.
But later the Renfe train was ordered to proceed in "error", according to Spain's transport minister.
The audio recordings were published by several Spanish news outlets including El Pais and RTVE.
In one, a control centre operator is speaking to the driver of the Renfe train, which was having some technical difficulties.
After some exchanges, the control operator tells the driver: "Continue your journey and then proceed under [Lateral Signalling Block], at normal speed with normal operation."
The…