MADRID, Spain -- Spanish investigators were trying Wednesday to identify an employee of the state rail company Renfe who was on the phone to a driver at the moment his train crashed last week, killing 79 people in the country's worst rail accident in decades.

A court spokeswoman said the employee called driver Francisco Jose Garzon Amo two minutes before the train barrelled into a dangerous curve at almost twice the speed limit, causing it to derail and slam into a wall and embankments. She said the call had not ended when the accident occurred.

Police discovered the call on opening the train's data-recording "black boxes" Tuesday.

The derailment occurred near Santiago de Compostela, a city in northwestern Spain's Galicia region, late last Wednesday. The investigations have focused on whether the accident was caused by human error other whether there may have been a mechanical or technical failure.

The train had been going as fast as 192 kph shortly before the derailment, and the driver activated the brakes "seconds before the crash," according to a Santiago de Compostela court statement Tuesday after the data recorders were examined. The speed limit on the section of track where the crash happened was 80 kph. The court said in its preliminary findings that no technical failure had been found so far.

Garzon was provisionally charged Sunday with multiple counts of negligent homicide. Some 61 people injured in the crash are still hospitalized, 13 of them in critical condition.

"There are elements -- such as the recorded conversation between the driver and Renfe's control centre, the box that records the train's data, and the driver's own testimony -- that indicate that things were not done properly," Galicia regional government president Alberto Nunez Feijoo told Onda Cera radio on Wednesday.

"The driver has acknowledged his mistake," he added.

Spanish news reports say Garzon conceded to the judge that he had been going too fast but could not stop in time, but the court would not comment on the reports.

Garzon was not sent to jail or required to post bail because none of the parties involved felt there was a risk of him fleeing or attempting to destroy evidence, according to a court statement.

Phone contact between drivers and control centres is not unusual but not recommended if it poses a risk, a Renfe spokeswoman said Wednesday. She said that a driver is under no obligation to answer an incoming call if he deems it best not to do so.

The driver has access to two phones: one fixed in the driver's cabin and the other a cellphone. She said there is no contact by computer in the form of emails or messages.

A court statement Tuesday said the black boxes showed the driver received a call from a Renfe official on his work phone in the cabin, not his personal cellphone, to tell him what approach to take toward his final destination.

The Renfe employee on the telephone "appeared to be a controller," a person who organizes train traffic across the rail network, said a statement from a court in Santiago de Compostela, where the investigation is based. "From the contents of the conversation and from the background noise it seems that the driver (was) consulting a plan or similar paper document."

The court spokeswoman said there were no details as to what paper documents the driver might have been looking at. She said this idea was a conclusion drawn from the conversation and the background noise of paper being handled. She said the black box had no video footage.

The accident has shaken Spain and, in particular, Santiago de Compostela, the last stop for the faithful who make it to the end of the El Camino de Santiago pilgrimage route that has drawn Christians since the Middle Ages. The crash occurred on the eve of annual festivities at the shrine, which subsequently were cancelled.

Authorities have said that a high-tech automatic braking program called the European Rail Traffic Management System was installed on most of the high-speed track leading from Madrid north to Santiago de Compostela -- the route Garzon's train took. But the cutting-edge coverage stops 5 kilometres south of where the crash occurred, placing responsibility on the driver to reduce speed.

The Spanish rail company has said the brakes should have been applied four kilometres before the train hit the curve.

The investigation could last several more weeks.