BMC officials monitor the movement of people on the roads inside a "war room" in Mumbai.

Highlights Mumbai is home to around 12 million people, nearly 65% live in slums

Coronavirus cases in city ticked up above 1,900, including 113 deaths

In Dharavi, experts fear the numbers could climb quickly

In an air-conditioned government building in Mumbai, a dozen officials are glued to a giant screen showing live drone and CCTV footage of crowded slums, the frontline in the city's battle to contain the spread of the coronavirus.

When cameras captured dozens of shoppers thronging a market in Mumbai's Dongri area last week, violating the countrywide lockdown begun on March 25, officials called in the police to disperse the crowd.

Twenty minutes later, the footage from Dongri showed only a handful of people still milling around. To help enforce a lockdown in what is one of the most densely populated areas on earth, authorities are using drones, re-oriented traffic cameras, and heat maps, but these can fall short when it comes to maze-like slum alleys.

"Hundreds will fall through the cracks, thousands but as long as it is not in millions we are safe," Praveen Pardeshi, who heads the city's main civic body, told Reuters in an interview.

Mumbai is home to around 12 million people, of which some 65% live in slums.

A further six million people are estimated to live in peripheral districts. Confirmed cases in the city have ticked up above 1,900, including 113 deaths, making up around 15% of India's more than 12,000 known cases. Dharavi, often considered Asia's biggest slum with an estimated 1 million residents, has reported 71 cases and experts fear the number could climb quickly. Authorities stress that part of Mumbai's high rates stem from more aggressive testing.

The city has conducted 2,374 tests per million, versus 448 per million in New Delhi, according to a Mumbai government report reviewed by Reuters on Thursday.

Around 82% of coronavirus patients in Mumbai are stable, with just 2% requiring critical care, the data shows.

"If this percentage remains of stable cases, then we are through," said Pardeshi.

Authorities have cordoned off parts of the slums, set up special fever clinics and created massive quarantine centres in a stadium and empty government buildings. But the restrictions are hard to observe when living at such close quarter.

On a recent afternoon in a narrow passage encumbered by goats and electrical wire, police officers pleaded with a dozen Dharavi residents to go home.Asif Siddiqui, a construction shop worker who lives in a one-room apartment with six family members, stayed put."They ask us to keep one meter distance, but my home is two meters long.

"We are trying to co-operate, but it is impossible to stay home in a place like this," said Siddiqui.