Deaths from coronavirus in New Delhi are almost twice as high as official figures show, a city leader said, as India overtook Britain with the fourth-highest number of cases worldwide.

With India's lockdown being widely eased, the government has been reporting almost 10,000 new confirmed cases every day with infections totalling almost 300,000, including 8,500 deaths. Densely populated megacities such as Delhi and Mumbai are the worst affected, stretching hospitals to breaking point.

But data in Delhi is understating the true scale of the outbreak, said Jai Prakash, standing committee head of the North Delhi Municipal Corporation, one of the three sub-districts that make up the capital. Citing data from the city's busy crematoriums and cemeteries, Prakash said Thursday that just over 2,000 people have died from the virus across the city -- almost twice the official toll.

"These were corona positive cases. We have a separate record of funerals of some another 200 suspected cases," Prakash told reporters.

But the party that governs Delhi as a whole, which has come under fire for its handling of the health crisis, rejected the claims. "This is a time to unite and save lives of people. This is not the time to make allegations," the Aam Aadmi Party said in a statement.

Financial capital Mumbai is officially India's worst affected city with almost 2,000 fatalities. Parts of the Dharavi area in Mumbai, one of Asia's largest slums, have been under strict months-long lockdown. The number of new cases has been easing, with 20 new infections confirmed on Friday.

The death toll in the southern city of Chennai is at least 460, more than double the official figure, media reports said this week. Despite the surge in cases nationally, which is being mirrored elsewhere in South Asia, Prime Minister Narendra Modi's government has declared the lockdown a success and has been steadily lifting restrictions.