Rail firms are being urged to consider installing devices which vibrate a train driver's seat if they fall asleep.

The fatigue monitors were introduced to the Croydon tram network in south London following a crash in November 2016.

An accident report found the driver had a "micro-sleep" moments before the tram went too fast round a bend and derailed.

The monitors use infrared beams to scan drivers' eyes to check they are concentrating.

If they detect that a driver may have fallen asleep or become distracted, they sound an alarm and vibrate the driver's seat.

HM Chief Inspector of Railways Ian Prosser has asked operators of mainline trains to consider using the devices.

He told radio station LBC: "We have developed a set of principles which we want to discuss with all partners in the industry and do some pilots, and we're working on that as we speak."

A service was held in Addiscombe to mark the two year anniversary of the crash earlier this month.

Despite introduction of fatigue monitors, concerns remain about whether sufficient improvements have been made to tram safety.

Almost a year since the Rail Accident Investigation Branch (RAIB) report into the crash, the first and 'most important' of the RAIB's 15 safety recommendations, to create a new tram safety body, is yet to be implemented.

MP Sarah Jones has criticised a delay in government funding, which has stalled the establishment of the new body.