Reported by BBC World
Watch: 'Chaotic scenes' at site of Spain's deadly train crash
Audio recordings published in Spanish media reveal conversations between train drivers and a railway control centre in the minutes leading up to a deadly train crash that killed at least 69 people and injured dozens.
Officials are investigating the cause of the disaster, which occurred when a train travelling from Madrid to Seville barrelled into a stationary train on Wednesday morning.
More from the original report
Three audio recordings between the control centre in Madrid and two train drivers appear to show that one high-speed train was given clearance to move even though another some 25km (15 miles) up ahead had stalled.
Prime Minister Pedro Sánchez, who travelled to the area of the crash, said authorities were working "day and night" to "get to the bottom of every last detail of this tragedy".
The release of the recordings comes as Spain begins three days of national mourning for one of the worst rail disasters in Europe's modern history.
One train, run by state-owned operator Renfe, had 397 passengers on board. Ahead of it on the same line was a train run by private operator Iryo, with 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.
Audio recordings published by Spanish news outlets including El Pais and RTVE reveal the conversations that took place between the two train's drivers and the control centre in the Spanish capital ahead of the crash.
In one recording, a control centre operator is speaking to the driver of the Renfe train, which was travelling behind the other train and 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 driver replies, "At normal speed?" To which the controller says: "Yes."
The Lateral Signaling Block is a back-up or alternative train system used when the automatic signalling or…