A coronavirus isolation centre in Mumbai, in Maharashtra state -- one of the worst hit in India. (Photo: AFP)

India's nationwide lockdown, the biggest imposed in the world over the coronavirus pandemic, will be extended until at least May 3, Prime Minister Narendra Modi said Tuesday.

The current three-week-old lockdown of the nation of 1.3 billion people had been scheduled to end at midnight Tuesday.

"From the economic angle, we have paid a big price," Modi said in a nationwide address. "But the lives of the people of India are far more valuable."