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.

Puente had said that the decision to instruct the trains to move again, without any speed restrictions, was “inexplicable”.

The leaking of the audio recordings has been criticised by some Spanish politicians, with Alberto Ibáñez, a member of Congress for the left-wing Sumar platform, writing on X that they were “despicable”.

Meanwhile, Irene Montero – the prime ministerial candidate for the left-wing Podemos party – said responsibility for the crash should not be placed on one worker, adding that train drivers and experts have been warning against the liberalisation of the railway sector for years.

On Friday Puente said he was “not going to use any worker as a shield”.

But he said “many questions” arose as a result of the tragedy and he wanted to look at them “one by one”.

“If the investigation shows there is human error we will act in consequence of that,” he said.

The country is observing three days of mourning, as the families of victims and the survivors of the crash struggle to comprehend how it could have happened.

The conservative People’s Party joined calls for Puente’s resignation after trade union CSIF called for the same earlier this week.

But Puente said on Friday he would not budge from his position.

“The easy thing for me would be to leave, but neither that fits with my character nor is it what the Prime Minister has asked me to do,” he said.

“I feel immense pain and immense sadness for the victims and their relatives… I cannot let this pain paralyse me though. We have to find solutions to this problem.”

Additional reporting by Sergi Forcada Freixas