NEW DELHI/KABUL: Authorities enforced lockdowns across most of India, Nepal and parts of Pakistan on Tuesday to halt the spread of coronavirus in one of the world's most densely populated regions, as four NATO personnel tested positive in Afghanistan.

Health researchers have warned that more than a million people in India could be infected with the coronavirus by mid-May, prompting Prime Minister Narendra Modi's government to shut down all air and train travel, businesses and schools.

Modi was due to address the nation for a second time in a week later on Tuesday on the risks to the country of 1.3 billion people from the virus that emerged in China late last year and has spread to 194 countries.

India has found 482 cases of the coronavirus and nine people have died from the COVID-19 disease it causes but alarm is growing across the region about prospects for its spread into impoverished communities and the ability of resource-starved public health sectors to cope.

Already health officials said the virus was spreading out of big Indian cities where it first appeared into the small towns that dot the landscape.

"This trend is worrying as rural areas have limited infrastructure to deal with the outbreak," said a health official in the western state of Maharashtra who declined to be identified saying he was not authorised to speak to journalists.

More than 377,300 people have been infected by the coronavirus globally and 16,520 have died, according to a Reuters tally.

Across South Asia, home to a quarter of the world's population, authorities are scrambling to raise their defences as the virus spreads.

NATO IN AFGHANISTAN

Four NATO service members in Afghanistan tested positive for coronavirus shortly after entering the country, the first confirmed cases in the mission, NATO said in a statement.

"The service members were newly arrived in country, and were in a precautionary screening facility when they became symptomatic, were moved to isolation and were tested," the statement said.

Around 1,500 NATO service members, most of whom had recently arrived in Afghanistan, were in screening facilities as a precautionary measure, NATO said.

Afghanistan's health ministry said that WHO had estimated that 80 percent of the war ravaged country's 32 million population could be infected with the virus in the next five months. So far it has had 42 cases and one death.

Invoking a 56-year-old law, Nepal ordered a nationwide lockdown to contain the spread of the virus after reporting a second case in the Himalayan nation of 30 million people.

It closed its borders with India and China earlier in the week saying a large number of people, mostly Nepali migrant workers, were trying to rush back home from India.

Bangladesh deployed the military to ensure social distancing and strengthen the coronavirus preventive measures, the military's information office said.

The Pakistani army is also helping to impose nationwide restrictions to contain the spread of the coronavirus following a request from the government.

Pakistan, with nearly 900 cases, has shut schools, malls, restaurants, cinemas, marriage halls, swimming pools and markets with only food and medical stores allowed to remain open.

CRACK DOWN ON DELHI PROTEST

Earlier on Monday, police in the Indian capital broke up the longest-running protest against a new citizenship law, citing a ban on public gatherings because of the coronavirus.

Dozens of people, many of them women, had been staging a sit-in protest since early December on a street in the Shaheen Bagh neighbourhood, turning it into a focal point for opposition to the law seen as discriminating against Muslims.

Hundreds of police in riot gear surrounded the protesters and told them to leave, said Delhi's joint police commissioner D. C. Srivastava.

"It is a dangerous environment, with this coronavirus," he told reporters.

Confirmed COVID-19 cases in South Asia:

*Pakistan - 875

*India - 482

*Sri Lanka - 91

*Afghanistan - 42

*Bangladesh - 33

*Maldives - 13

*Nepal - 2

*Bhutan - 2

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TOTAL - 1,540