An Australian human rights group, founded by billionaire business magnate Andrew Forrest and backed by Hollywood actor Russell Crowe, has released research estimating that almost 46 million people are living as slaves.

The 2016 global slavery index, funded by Forrest’s Walk Free Foundation, says 45.8 million people are trapped in some form of slavery.

The report ranks incidences of slavery in 167 countries, with India having the highest number of slaves while North Korea has the highest percentage of slaves per capita. This year’s estimates are nearly 30% higher than in the previous report, which estimated 35.8 million people living in slavery in 2014.

Forrest says the rise is partially due to more accurate methodology but he also believes the number of people trapped in slavery is increasing year on year.

“It is time to draw a line and say, no more,” he said. “This isn’t Aids or malaria, it is a man-made problem that can be solved, and it’s time to take real action to free the world from slavery once and for all.”

The index was launched in 2013 after Bill Gates, another billionaire philanthropist, challenged Forrest to quantify the scale of modern slavery. This year’s index was launched in London on Tuesday by Crowe with video messages of support from Tony Blair, Bono, supermodel Karlie Kloss and Richard Branson.

Forrest, who says he found and addressed slavery in his own supply chains, warned businesses that they must step up their efforts to address slavery or face the consequences. He also called on consumers to question their buying habits.

“At one point, it was common to see Australian truck drivers throwing litter out of the windows of their cars because everyone else was doing it. Now, there has been a huge public outcry against this behaviour and it has stopped. The same can be done for slavery,” he said.

“We need to make it unacceptable for people to buy something without asking the company where it was made and who made it and if they can’t answer that question clearly then the next question must be ‘how do you know it wasn’t made with slave labour?’”

Walk Free said slavery is found in all 167 countries in the index, with India home to 18.4 million slaves. This year’s index also claims that over half of the 45.8 million people living in modern slavery are in five countries: India, China, Pakistan, Bangladesh and Uzbekistan.

It calculated that more than 4% of North Korea’s population is enslaved, with Uzbekistan and Qatar the other countries with the highest prevalence of modern slavery per capita.

The index has faced criticism for its methodology and rankings system since it launched. Despite naming 167 countries, this year’s index was based on interviews conducted by pollster Gallup with more than 42,000 people in 25 countries. In some cases, rankings and prevalence estimates are calculated using data from surveys conducted in other countries deemed to have an equivalent “risk profile”.

Kevin Bales, an anti-slavery campaigner who worked on collecting data for this year’s report, said he is “very confident” the estimations were an accurate reflection.

“Over the last few years we have really honed our methodology and have build a solid framework to build on year on year,” he said. “Measuring the problem is a hugely important factor in beginning to effectively tackle this enormous problem.”

Although modern slavery constitutes a huge illegal industry, deemed the third most profitable criminal industry behind drug and arms trafficking by the UN, data remains patchy.

The International Labour Organisation (ILO) estimates that 21 million people are trapped in forced labour and other forms of modern slavery. The index says it hopes to work with the ILO to provide a single set of global estimates.