Almost 46 million people are living as slaves globally with the greatest number in India but the highest prevalence in North Korea, according to the third Global Slavery Index launched on Tuesday with Australian actor Russell Crowe.
The index, by Australia-based human rights group Walk Free Foundation, increased its estimate of people born into servitude, trafficked for sex work, or trapped in debt bondage or forced labor to 45.8 million from 35.8 million in 2014.
Andrew Forrest, founder of Walk Free, said the rise of nearly 30 percent was due to better data collection, although he feared the situation was getting worse with global displacement and migration increasing vulnerability to all forms of slavery.
Forrest, an Australian mining billionaire and philanthropist, urged businesses to check their supply chains for worker exploitation, saying he found thousands of people trapped in slavery making goods for his company Fortescue Metals Group.
Incidences of slavery were found in all 167 countries in the index, with India home to the largest total number with an estimated 18.4 million slaves among its 1.3 billion population.
The 2016 index was based on interviews with about 42,000 people by pollster Gallup in 53 languages in 25 countries.The United Nation's International Labour Organization estimates 21 million people globally are victims of forced labour but this does not take into account all forms of slavery.