A train crash in California that killed 25 people and injured 135 may have been caused in part by a text message.

Investigators with the US National Transportation Safety Board have confirmed that Robert Sanchez sent a text message seconds before the commuter train he was driving ran through a signal and collided head on with a freight train near Los Angeles. Sanchez was killed in the crash.

The accident was the worst railroad disaster in the US since 1993, when a train derailment in Alabama killed 47 people.

According to Reuters, Sanchez was found to have sent a text message just 22 seconds before the trains collided.

The driver was also believed to have received seven messages and sent five more in the 90-minute period leading up to the collision, and dozens more while running another train that morning.

The incident has stoked the debate over the use of mobile phones while operating vehicles. In California, it is illegal for anyone to use a handset while driving a car, although headsets are allowed.

The UK has similar laws against mobile phone use by drivers, but these are largely ignored.

California state officials have issued a temporary order preventing train drivers from using mobile phones while working.