Factbox: Which countries have the most slaves? Key figures from global slavery index

Nearly 46 million people around the world are living as slaves, forced to work in factories, mines and farms, sold for sex, trapped in debt bondage or born into servitude, according to the third Global Slavery Index released on Tuesday.

The survey by Walk Free Foundation, the Australia-based human rights group, increased the estimated number of people in modern slavery to 45.8 million from 35.8 million in 2014.

Here are some key figures from the index:

* Asia is home to an estimated two-thirds of the total number of people living in modern slavery

* Sub-Saharan Africa accounts for about 15 percent of the world's slaves

* India is the country with the greatest number of people living in some form of modern slavery, estimated at 18.3 million

* China came second with an estimated 3.4 million slaves and Pakistan third with an estimated 2.1 million slaves

* Rounding out the top 10 were Bangladesh, Uzbekistan, North Korea, Russia, Nigeria, Democratic Republic of the Congo and Indonesia

* North Korea is the country with the highest estimated proportion of modern slavery with nearly one in every 20 North Koreans, or 4.37 percent of a 25 million population, living in slavery

* In terms of concentration, second was Uzbekistan with 3.97 percent of its population in slavery amid reports of forced labour in its cotton industry, then Cambodia with 1.6 percent, India with 1.4 percent and Qatar with 1.36 percent

* Governments taking the most steps to combat modern slavery were the Netherlands, the United States, Britain, Sweden, Australia, Portugal, Croatia, Spain, Belgium and Norway

* The least action was being taken by the governments of North Korea, Iran, Eritrea, Equatorial Guinea, Hong Kong, Central African Republic, Papua New Guinea, Guinea, the Democratic Republic of the Congo, and South Sudan.