India's northern states, including the national capital, were hit by a massive power outage Monday in what is said to be the worst blackout due to the failure of the northern grid since 2001.

The outage affected over 300 million people across the states of Indian-controlled Kashmir, Punjab, Haryana, Uttar Pradesh, Himachal Pradesh and Rajasthan, as well as the central government- controlled Chandigarh.

"The blackout happened from 2.30 a.m. (local time) following a major disturbance in the Northern Grid. In fact, a major fault near the town of Agra led to power being snapped. However, partial supply of power was restored by 9 a.m. (local time)," an official said.

"At least 200 trains have been delayed due to the blackout in the states," he added.

The Indian capital was among the worst hit as the power outage affected train services, the Metro railway, and even caused traffic jams on the roads, giving a harrowing time to office-goers.

The Indian capital generates less than 20 percent of its own power requirement and is dependent on the Northern Grid for the rest.

Meanwhile, Indian Power Minister Sushil Kumar Shinde has said that a three member committee has been mandated to investigate the fault. "We have set up a three-member committee to look into the collapse of the northern power grid. The panel will submit its report in the next 15 days," he told the media.

The Power Minister added that power supply will be resumed in the next three to four hours across the affected region.

Power cuts are common in Indian cities due to a fundamental shortage of power and an aging grid.

Experts say that India urgently needs a huge increase in power production. Even Prime Minister Manmohan Singh has long said that India must look to nuclear energy to supply power to the people.