HONG KONG (CNN) -- A new report claiming to be the most comprehensive look at global slavery says 30 million people are living as slaves around the world.

The Global Slavery Index, published by the Australia-based Walk Free Foundation, lists India as the country with by far the most slaves, with an estimated nearly 14 million, followed by China (2.9 million) and Pakistan (2.1 million).

The top 10 countries on its list of shame accounted for more than three quarters of the 29.8 million people living in slavery, with Nigeria, Ethiopia, Russia, Thailand, Democratic Republic of Congo, Myanmar and Bangladesh completing the list.

In terms of countries with the highest of proportion of slaves, Mauritania in West Africa topped the table, with about 4% of its 3.4 million people enslaved, followed by Haiti, Pakistan, India and Nepal.

The index, whose authors claim it contains the most authoritative data on slavery conditions worldwide, is the product of Australian mining magnate and philanthropist Andrew Forrest's commitment to stamp out global slavery.

Forrest, ranked by Forbes as Australia's fifth richest man, with an estimated net worth of $5.7 billion, adopted the cause after his daughter volunteered in an orphanage in Nepal in 2008, coming into contact with child sex trafficking victims. Forrest is a signatory to the Giving Pledge started by billionaire investor Warren Buffett, whose members commit to donating at least half their wealth to philanthropic causes.

The index, which draws on 10 years of research into slavery conditions around the world and was produced by a team of 4 authors supported by 22 other experts and advisers, is the inaugural edition of what will be an annual report into slavery. It ranks 162 countries according to the number of people living in slavery, the risk of enslavement and the robustness of government responses to the problem.

Walk Free policy and research manager Gina Dafalia told CNN the report was intended to shine a spotlight on the issue, and quantify the extent of the problem in different countries before programs were put in place to tackle the problem. So far, she said, Walk Free -- and its partners Humanity United and the Legatum Foundation -- had pledged a total of $100 million to stamp out the practice.

"When we started working in this area we realized that we didn't have a good understanding of what exactly the situation of slavery is in the world," she said. "We needed that information before we started doing any interventions."

The index gives a higher estimate of the global number of slaves than other reports -- a report by the International Labor Organization last year pegged the number at 20.9 million.

Dafalia said this was a result of the Global Slavery Index using a broader definition of slavery, which included human trafficking, forced labor, as well as practices such as forced marriage, debt bondage and the exploitation of children.

"Our definition of modern slavery includes, for example, forced and servile marriage, a concept not included in the ILO estimate, given the focus on 'forced labor,'" she said.

The explicit definition used in the report was "the possession and control of a person in such a way as to significantly deprive that person of his or her individual liberty, with the intent of exploiting that person through their use, management, profit, transfer or disposal. Usually this exercise will be achieved through means such as violence or threats of violence, deception and/or coercion."

Asked why 30 million continued to live in conditions of slavery in 2013, Dafalia said the reasons varied from country to country, but one constant was that it remained a "hidden problem."

In some of the worst-hit countries, the report said, the affected parties were citizens ensnared in endemic, culturally-sanctioned forms of slavery -- "the chattel slavery of the Haratins in Mauritania, the exploitation of children through the restavek practice in Haiti, the cultural and economic practices of both caste and debt bondage in India and Pakistan, and the exploitation of children through vidomegon in Benin."

In other examples, including Nepal, Gabon and Moldova, it was migrants who were most vulnerable to exploitation. In many examples, noted the report, child and forced marriage was prevalent and child protection practices weak.

It noted that in India, the country with the most slaves, the risk of enslavement varies markedly from state to state.

The Middle East and North Africa, it said, showed the highest measured level of discrimination against women, with one result being a high level of forced and child marriages within the region, and widespread exploitation of trafficked women as domestic workers and prostitutes. Vulnerable male migrants also frequently found themselves in exploitative working conditions.