Up to 340 people are living in slavery in Ireland, according to a new global slavery index.

The Immigrant Council of Ireland has said the index highlights the need for urgent political action.

The council's chief executive Denise Charlton said it confirms that the most prevalent form of trafficking in Ireland is for sexual exploitation, with the victims mostly women and girls.

It is calling for laws aimed at ending demand for sex-trafficking.

Nearly 30 million people are living in slavery across the world, according to the index.

Many of them are men, women and children trafficked by gangs for sex work and unskilled labour.

The index by anti-slavery charity Walk Free Foundation found that ten countries accounted for 76% of the 29.8m people living in slavery.

They are India, China, Pakistan, Nigeria, Ethiopia, Russia, Thailand, the Democratic Republic of Congo, Burma (also known as Myanmar) and Bangladesh.

Modern slavery was defined as human trafficking, forced labour, and practices such as debt bondage, forced marriage and the sale or exploitation of children.

The charity ranked 162 countries on the number living in slavery, the risk of enslavement and the strength of government responses to combating the illegal activity.

Researcher Professor Kevin Bales said he hoped the index would raise public awareness as numbers were at an all-time high.

He dismissed the view that poverty was the key factor behind slavery and instead blamed corruption, calling for laws to stop organised gangs.

The professor of contemporary slavery at the Wilberforce Institute for the Study of Slavery and Emancipation at the University of Hull in England added: "Fundamentally this is a violent crime issue."

The report found Mauritania in West Africa had the highest number of slaves proportionately, with up to 160,000 enslaved in a population of 3.8m.

The highest absolute numbers were almost 14m in slavery in India and 3m in China.

"By far the largest proportion of this problem [in India] is the exploitation of Indian citizens within India itself, particularly through debt bondage and bonded labour," the report noted.

In China, there was forced labour of men, women and children, including domestic servitude and forced begging, sexual exploitation of women and children and forced marriage.

Coming last in the index were Iceland, Ireland and Britain, although Prof Bales stressed they were not slavery-free.

Up to 4,400 people are estimated to be enslaved in Britain, the victims mainly from Africa, Asia and Eastern Europe.

They are forced into sex work, domestic servitude, or low-paid jobs in agriculture, construction, restaurants and nail salons.

"Hopefully this report will be a wake-up call for rich countries as well," Prof Bales added.