Spanish police are waiting to question one of the drivers of a train that derailed, killing at least 80 passengers, amid media reports it was travelling at twice the speed limit.
The driver, lightly injured, "would be questioned by police in hospital where he has been placed under surveillance", the High Court in Galicia said in a statement on Thursday.
The investigating magistrate in the case has not ordered his detention, the statement added.
"The judge has asked police to take his statement," in the presence of a lawyer, a court spokeswoman said. After that, he will have to give his account before the magistrate, she added.
A police source said they had originally expected to question him on Thursday.
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Renfe, the state railway company, says it's too early to determine the cause of the tragedy.
But secretary of state for transport Rafael Catala has told radio station Cadena Ser that the early signs suggest the crash had been caused by the train going too fast.
According to several media reports, the train was going at twice the speed limit when it crashed near the northwestern city of Santiago de Compostela late on Wednesday.
Prime Minister Mariano Rajoy, a native of the city, announced the launch of two probes into the accident and declared three days of national mourning.
A local government official in the Galicia region said there are 80 confirmed dead, making it the deadliest rail accident since 1944 when hundreds were killed in a train collision, also between Madrid and Galicia.
Regional health minister Rocio Mosquera says another 178 are injured, including 94 who remain in hospital - and warned that the death toll could rise.
The driver to be questioned was trapped in the cab after the accident, El Pais newspaper reported.
He had told railway officials by radio that the train had taken the bend at 190km/h, unidentified investigators told the newspaper.
The speed limit on that section of track is 80 kilometres an hour.
A security video taken at the moment of the accident shows the train negotiating a curve before a number of carriages come off the rails and drag the rest off with them.
