Power has been fully restored to three electricity grids which had failed causing a blackout affecting more than 600 million people in more than 20 states and union territories. Power System Operation Corporation, PSOC,chief SK Soonee said this morning that power supply has been restored fully .

Soonee said that power was restored by engineers from PSOC, who worked overnight. PSCO is the state-owned company which manages the country's electricity generation system. Three power grids collapsed from around 1:00 pm yesterday, and electricity was gradually restored during the course of the day. The government has announced an investigation into the cause of the crisis.

AIR correspondent reports that states overdrawing electricity from the regional grids is thought to have caused the collapse. An earlier blackout on Monday on the northern grid, described as the worst in a decade, hit in the middle of the night and left nine states without power for six hours.