The south Indian state was shut down on Monday, with officials withdrawing public transport services and ordering retail outlets to shut, in a bid to lower the daily infection rate from the disease which has been above 400,000 for at least a week

The Foxconn facility in Tamil Nadu was set up to cater to the market in India, the second biggest market in the world. Foxconn also has a facility in Andhra Pradesh, another southern state.

Reuters said more than 100 Foxconn workers had tested positive for the coronavirus and an entry ban had been placed on the factory in Chennai, formerly Madras, until the end of May.

Apple is not the only smartphone manufacturer to be hit by the rampant spread of COVID-19 in India. As iTWire reported on Monday, Xiaomi, realme, OPPO and vivo, all of which have been increasing sales in India in recent years, could also be affected.

One source told Reuters: "Employees are only allowed to leave, but not to enter the facility since yesterday (Monday). Only a small part of output is being kept."

India is not a very big market for the iPhone, but the setting up of the Foxconn facility has helped push sales.

It has also helped Apple's cause as the company has had to take into account the tensions between the US and China and shift some of its production out of the Middle Kingdom.

The Taiwan-based technology research firm Trendforce said it was revising its forecasted year-on-year growth in global smartphone production for 2021 from 9.4% down to 8.5%, with a yearly production volume of 1.36 billion units and potential for further decreases ahead

"Judging from the current state of Indian smartphone manufacturing, TrendForce expects the second wave to reduce the country’s smartphone production volume for 2Q21 and 3Q21 by a total of 12 million units, in turn resulting in a 7.5% year-on-year decrease in smartphone production in India for the whole year," it said in a statement on Monday.