Mumbai, India’s financial hub, rolled out precautionary measures on Tuesday in the wake of the discovery of a mutant COVID-19 virus in Britain.
India has so far reported more than 10 million COVID-19 cases, second only to the United States.
British experts say the new strain is 70 per cent more transmissible.
India is among dozens of countries to have suspended flights to and from Britain, with the new controls set to take effect at 11.59 pm (1829 GMT).
All passengers who arrived on flights from Britain to Indian cities on Monday and Tuesday are being quarantined and have to undergo RT-PCR tests.
Mumbai, which has been one of the epicentres of the virus, has imposed a night-time curfew until Jan. 5.
All shops except medical stores and a few other essential services will be closed and all non-essential travel barred between 11.00 pm and 6.00 am within the city limits, the government of Maharashtra said.
No more than five people can assemble outside their homes during these hours.
More than 1,000 people are expected to arrive from Britain on five flights to Mumbai before the flight ban sets in. They will be sent to institutional quarantine.
Five passengers on a flight that reached New Delhi late on Monday tested positive, a Delhi government spokesperson said.
They have been quarantined and their samples had been sent to the National Centre for Disease Control to identify the strain of the virus.
The Tamil Nadu government has decided to test all passengers who have arrived at Chennai airport from Britain in the past 15 days.(dpa/NAN)