He has been piloting trains independently since September 2008. On Wednesday, he began his shift at 2.55 p.m. and this was his first trip of the day.

'The DMRC has zero tolerance for negligence and today's was a serious lapse on the driver's part, for which he is likely to lose his job,' the official told IANS.

The DMRC has ordered an inquiry. An engineer's team is likely to submit its report Thursday.

The Yamuna Bank-Dwarka line, that runs via the busy Connaught Place commercial district in central Delhi, is one of the busiest routes in the capital. On an average, as many as 350,000 people travel by this route daily.

The Metro service on the track was disrupted till 6.30 p.m. Trains on the route were delayed even as the derailed train was put back to the tracks.

The accident occurred a month after Delhi Metro's July 12 tragedy in which six workers died when a beam of an under-construction elevated track collapsed in south Delhi.

Over 850,000 people commute on the Delhi Metro's three routes that run between southwest, east, north and central Delhi.