NEW DELHI: India's energy crisis spread over half the country Tuesday when both its eastern and northern electricity grids collapsed, leaving 600 million people without power in one of the world's biggest-ever blackouts. 

The power failure has raised serious concerns about India's outdated infrastructure and the government's inability to meet an insatiable appetite for energy as the country aspires to become a regional economic superpower.

The outage in the eastern grid came just a day after India's northern power grid collapsed for several hours. Indian officials managed to restore power several hours later, but at 1:05 pm, Tuesday the northern grid collapsed again, said Shailendre Dubey, an official at the Uttar Pradesh Power Corp. in India's largest state. About the same time, the eastern grid failed as well, said S K Mohanty, a power official in the eastern state of Orissa. The two grids serve about half India's population.

Traffic lights went out across New Delhi. The city's Metro rail system, which serves about 1.8 million people a day, immediately shut down for the second day in a row. Police said they managed to evacuate Delhi's busy Barakhamba Road station in under half an hour before closing the shutters.

S K Jain, 54, said he was on his way to file his income tax return when the Metro closed and now would almost certainly miss the deadline.

The new power failure affected people across 13 states — more than the entire population of the European Union. They raised concerns about India's outdated infrastructure and its insatiable appetite for energy that the government has been unable to meet.

India's demand for electricity has soared along with its economy in recent years, but utilities have been unable to meet the growing needs. India's Central Electricity Authority reported power deficits of more than eight per cent in recent months.

The power deficit was worsened by a weak monsoon that lowered hydroelectric generation and kept temperatures higher, further increasing electricity usage as people seek to cool off.

But any connection to the grid remains a luxury for many. One-third of India's households do not even have electricity to power a light bulb, according to last year's census.