Services on all six lines of Delhi Metro were affected on Monday due to a major failure in the Northern Grid that supplies power to the modern transport system.
No trains were available on any of the six lines on the network from 6:00 am, when the metro network resumes services after a few hours of break.
A Metro spokesman said the services would be fully restored only after the power supply resumes. While 25 per cent of the services have been restored but services were largely affected.
The delay in services will affect lakhs of commuters who depend on the metro. Delhi Metro carries more than 18 lakh people a day.