Two groups of Italian tourists were under quarantine in India Wednesday, with 16 testing positive for the new coronavirus, prompting authorities to tighten controls.

Italy is a hotspot of the virus with 79 deaths and over 2,500 infected, while India's case total stands officially at just 29 -- including the Italians and their Indian driver.

Confirming the new cases, Health Minister Harsh Vardhan said Wednesday that passengers on all international flights would now be screened.

Visitors from Italy, Iran, South Korea and Japan -- except diplomats and officials from international bodies -- were already barred, on Tuesday, along with those from China last month.

Vardhan said a husband and wife in the first Italian group -- who arrived last month and number around 20 -- fell ill while visiting the western state of Rajasthan, a popular tourist destination.

The remainder were moved to a quarantine centre in New Delhi, where 14 members plus their Indian driver were confirmed as being infected.

"We are awaiting test results of the others," a source told AFP said on condition of anonymity.

Separately authorities said that nine other Italians and their local guide have been quarantined in the central state of Madhya Pradesh for suspected exposure to the virus.

"Two of them are suffering from cough and cold. They have been quarantined as a precaution," local official Sheelendra Singh told the Press Trust of India.

- 'Report visitors' -

Worldwide around 3,200 people have died from the virus with more than 90,000 infections -- with China, South Korea, Italy, Iran and Japan the worst affected.

India confirmed three cases in late January and early February, all of whom arrived from China and who have since recovered.

But until last week no more infections were reported when an Indian man who returned from Italy via Austria to New Delhi tested positive.

The man has since infected six family members in Agra south of the capital and home to tourist hotspot the Taj Mahal.

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Hotels and tourist sites in Agra have been told to report any visitors from Italy, Iran or China, so that they can be screened, local medical official Mukesh Vats told PTI.

One other infection was confirmed in the southern state of Telangana, reportedly a software engineer who arrived from Dubai, where he met fellow technicians from Hong Kong.

Another was confirmed in Gurgaon outside Delhi with the local man having recently returned from Italy.

On February 4, India blocked the entry of new arrivals from China or anyone who had visited China in the preceding two weeks. It has also been screening arrivals from certain countries.

Gagandeep Kang, a leading infectious diseases expert and the first Indian woman to become a Royal Society Fellow, said that India's actions until now have been "entirely appropriate".

"But it is also a limited strategy. Maybe it's time to think about whether we should be doing more than this," Kang told AFP.

Prime Minister Narendra Modi tweeted on Tuesday that he had held an "extensive review regarding preparedness" for the virus and that different ministries and states were "working together".

"There is no need to panic. We need to work together, take small yet important measures to ensure self-protection," Modi said.

On Wednesday Modi said he would stay away from celebrations during Holi, one of India's biggest festivals when paint and water are thrown around in an explosion of colour.

Other top officials including Home Minister Amit Shah and Delhi Chief Minister Arvind Kejriwal said they would also skip the celebrations.