Coronavirus cases have been rising in some parts of the country since February.
Delhi reported 2,790 new coronavirus cases on Thursday - its highest daily figure this year - along with nine deaths amid a spurt in COVID-19 infections in the country. The city had logged 1,819 cases a day ago, making Thursday's jump a huge 53 per cent.
Cases have been on the rise in India since early February -- when new daily infections dropped below 9,000 -- to more than 72,000 on Thursday, the highest level since October.
Experts have warned that infections are increasing at a faster pace compared to last year, when single-day cases peaked at almost 1 lakh in September.
The state worst hit by the virus has been Maharashtra, home to the country's financial capital Mumbai.
The country's health secretary bluntly told the 28 states on Tuesday to get a grip on lax coronavirus prevention measures "right now" to prevent healthcare systems being overwhelmed by a surge in infections.
India's current caseload of 1.22 crore ranks third behind only the United States and Brazil, with testing unable to keep up with demand. The daily rise in cases has quadrupled in the space of a month.
"The current rise in cases ... has the potential of overwhelming healthcare systems unless checked right now," Health Secretary Rajesh Bhushan said in a letter to the states.
"Many districts in the country are seeing clusters of cases emerging because of specific events and/or places where crowding happens, or where a large number of people are in close contact coupled with a lack of a COVID-appropriate behaviour," he said.
Despite the warnings, top politicians including Prime Minister Narendra Modi himself have been addressing rallies and meetings of tens of thousands of people, sitting or standing shoulder-to-shoulder, with only a handful wearing masks.
Multi-phase elections in West Bengal, Assam, Tamil Nadu, Kerala and Puducherry began last week and will run through next month.
Vinod Kumar Paul, a senior government health official, told a news conference the situation across India was going "from bad to worse".
