The driver of a train that derailed in Spain killing 79 people was speaking on his work phone at the time of the accident and appeared to consult a map, a court said Tuesday after analysing the train's data recorders.

"Minutes before the train came off the tracks he received a call on his work phone to get indications on the route he had to take to get to Ferrol. From the content of the conversation and background noise it seems that the driver consulted a map or paper document," a court statement said.