A protracted blackout disrupted the lives of an estimated 300m people across northern India on Monday, as the aspiring superpower’s fragile infrastructure added to the woes of a government already struggling to manage the slowing economy, persistent inflation and the failure of the monsoon rains.

The blackout, which began at about 2.30am and lasted more than 12 hours in many areas, was the worst power failure in India for more than a decade.

Millions of people were left without electric fans or air conditioning in the 30°C heat, train services were disrupted, traffic was paralysed and New Delhi’s airport was forced to rely on back-up power systems for several hours. Emergency energy supplies from Bhutan helped the government restore power in many affected areas by early evening, but public discontent still simmered.