Mr Birendra Singh has a busy travel business in Ghaziabad, a suburb in India's Delhi region. But last month, ahead of the packed holiday season, the 35-year-old was forced to stop work for a day on two occasions.

The disruption was prompted by a decision of the state government of Uttar Pradesh, where Ghaziabad is situated, to cut Internet connectivity in an attempt to control spiralling protests against a controversial citizenship law.

"My entire work is reliant on being connected to the Internet. Coming here on those two days was as good as not coming to work," Mr Singh told The Straits Times recently, saying he lost about 2,000 rupees (S$38) in profit per day.

According to a recent report published by Top10VPN, a London-based organisation focused on Internet privacy, India lost more than US$1.3 billion (S$1.8 billion) last year because of Internet shutdowns, placing it third after Iraq and Sudan in terms of such losses incurred.

Globally, the report calculated more than 18,000 hours of Internet shutdowns last year, which imposed an estimated total cost of $10.8 billion. This amounted to a 235 per cent rise in impact compared to $3.24 billion in 2015-16.

The analysis also found that Internet shutdowns often occurred in response to protests or civil unrest, as "authoritarian regimes" looked to restrict information flow and maintain their grip on power.

India was also placed third, trailing Myanmar and Chad, when it came to the duration of Internet blackouts - a total of 4,196 hours. Top10VPN pointed out that India imposes Internet restrictions more often than any other country, with over 100 shutdowns documented last year.

Government officials in India say these shutdowns prevent the spread of violence but critics argue that they are used to stifle criticism online and make it difficult for citizens to organise protests.

"The Indian government is curtailing Internet access as a tool for political control," said Mr Ravi Nair, executive director of the South Asia Human Rights Documentation Centre.

"In a connected world, an Internet shutdown is the equivalent of putting you and the rest of the populace under house arrest irrespective of whether you are suspected of some crime or not," he said.

Top10VPN's report also factored in major region-wide instances of Internet shutdowns in India, including the Kashmir blackout, the recent shutdowns provoked by ongoing protests against the Citizenship Amendment Act, and precautionary disruptions around the time of the Ayodhya land dispute verdict in November last year.

But the report did not factor in many localised Internet shutdowns. Even India's capital New Delhi suffered a localised shutdown on mobile Internet last month as protests raged against the citizenship law.

"The full economic impact is therefore likely to be higher even than our US$1.3 billion figure," Top10VPN's report said.

News about Internet shutdowns in India has mainly been concentrated on those in Kashmir, where the clampdown has surpassed more than 150 days.

Internet services in Kashmir were suspended in August last year following the Indian government's decision to take away Jammu and Kashmir's statehood as well as its unique status, which accorded it some special rights.

A report from Reuters last month quoted an official from the Kashmir Chamber of Commerce and Industry as saying losses due to the ongoing shutdown had surpassed $3.2 billion.

The country's Supreme Court in a significant ruling last Friday said access to the Internet is a fundamental right and cannot be curbed indefinitely. It also asked the Jammu and Kashmir administration to review all orders regarding such curbs in the region within a week.

The Gauhati High Court in the state of Assam last month went one step further and ordered that Internet connectivity be reinstated after it was shut down in the state for more than a week following protests against the new citizenship law.