NEW DELHI (Reuters) - Grid failure hit India for a second day on Tuesday, cutting power to hundreds of millions of people in the populous northern and eastern states including the capital Delhi and major cities such as Kolkata.

The government said the northern, eastern and northeastern grids were hit, wider than Monday's blackouts.

Delhi's metro system ground to a halt and office buildings ran on backup generators a day after a 12-hour blackout caused commuter chaos in the bustling capital, underscoring overstretched infrastructure that has weighed heavily on India's economy.

"The northern grid has failed again," Arvinder Singh Bakshi, the chairman of the Central Electricity Authority, told Reuters.

The northern grid alone covers more than 300 million people from the mountains of Himachal Pradesh to the Ganges plains in Uttar Pradesh, which has a larger population than Brazil.

TV stations said the eastern grid was also affected and a Reuters reporter said some areas of the former capital Kolkata in the east of the country were without power.

(Reporting by Delhi Bureau and Sujoy Dhar in Kolkata; Writing by Frank Jack Daniel; Editing by Nick Macfie)