CNN) - The driver of a train that derailed in northwestern Spain last week, killing 79 people, was on the phone with railway staff when the train crashed, court officials announced Tuesday, citing information from data recorders.

The train was going 153 kph (95 mph) when it derailed, the superior tribunal of Galicia said.

That's nearly twice the speed limit on the curve where the accident happened.

Authorities have charged the train's driver, Francisco Jose Garzon, with 79 counts of homicide by professional recklessness and an undetermined number of counts of causing injury by professional recklessness.