LOS ANGELES - THE train driver blamed for the worst US train crash in 15 years was sending and receiving text messages seconds before his crowded commuter train skipped a red light and collided head-on with a freight train, federal investigators said on Wednesday.

The Metrolink commuter train plowed into a Union Pacific freight locomotive on Sept 12 in Chatsworth, California, killing 25 people and injuring 135 in the worst train accident since 1993.

A National Transportation Safety Board probe has focused on whether the engineer, identified as Mr Robert Martin Sanchez, 46, failed to heed trackside signals. Mr Sanchez was killed in the crash.

Cell phone records show Sanchez was sent a text message at 4.22.01pm, and received one at 4.21.03pm. The accident occurred at 4.22.23pm, according to Union Pacific train's onboard recorders.

He received seven and sent five text messages between 3.00pm and the time of the accident.

Mr Sanchez also received 21 text messages and sent 24 while he ran a train from 6.44am to 8.53am.

Since the timings were not all recorded on a common platform, the precise correlation between the events is not clear, investigators at the NTSB said.

Local TV station KCBS reported that a teenager claimed to have received a text message from the Metrolink engineer a minute before the collision.

Following the accident, California authorities temporarily banned railroad workers from using cellphones on duty. -- REUTERS