India's total Covid-19 cases passed 18 million on Thursday after another world record number of daily infections, as gravediggers worked around the clock to bury victims and hundreds more were cremated in makeshift pyres in parks and parking lots.

India reported 379,257 new infections and 3,645 new deaths on Thursday, health ministry data showed, the highest number of fatalities in a single day since the start of the pandemic.

The world's second most populous nation is in deep crisis, with hospitals and morgues overwhelmed.