India's northern electricity grid which covers an area home to more than 300 million people failed for the second day in a row on Tuesday, with the eastern network also down, an official said.

"We are busy with the revival right now... Both the Northern and Eastern grids have collapsed. Please allow us to address the problem," V.K.Agrawal, the general manager of the northern grid, told AFP.

In New Delhi, the metro came to a standstill and traffic lights were out.

"Drivers of all the metro trains have been asked to stop at the stations. No passengers will be allowed in the metro station until power is restored," a metro spokeswoman told AFP.

The eastern city of Kolkata was without power as were most parts of West Bengal, an official at the West Bengal State Electricity Supply Corp., B. Mukherjee, confirmed to AFP.