At least nine people have died in India after contracting COVID-19, which has infected more than 500 people across the South Asian country, and health experts warn that a big jump in cases could be imminent.

The world's second-most populous nation has so far seen low infections, but at the weekend it saw a big jump, prompting authorities to announce a lockdown in dozens of cities and districts until March 31.

The shut down came after millions of people observed a 14-hour "public curfew" on Sunday called by the government amid concerns India's underfunded and crumbling public health infrastructure might be overwhelmed.

The capital New Delhi, which has 31 cases, on Monday sealed the city's borders and imposed a lockdown on its nearly 20 million residents.

Authorities have banned gatherings of more than five people in several of India's states, including Maharashtra, the worst affected with 101 cases.

The southern state of Kerala, which has been praised for its proactive approach to the pandemic early on, has 97 cases. A large section of the state's residents work abroad, mainly in the Middle East.

In the financial hub of Mumbai, Maharashtra's capital, suburban trains, which usually carry 8 million people a day, were suspended until the end of the month.

Prime Minister Narendra Modi said on Monday that many Indians were not taking the lockdown seriously. "Please save yourself, save your family, follow the instructions seriously," he said on Twitter.

Global coronavirus infection have exceeded 325,000 with more than 14,500 deaths, the largest number of them in Italy.

Editor's note: This article and its map will be updated periodically throughout the day, but always check with local government officials for the most up-to-date numbers.