Extremist groups use apps to trade slaves

A new report on human trafficking has found that extremist groups are using social media apps to recruit and auction enslaved women.

There is growing evidence that extremist groups including IS and Boko Haram are reviving slavery. (AAP)

There is growing evidence that extremist groups including the Islamic State and Boko Haram are reviving slavery and organising slave markets, a United Nations University report on fighting human trafficking has found.

"There is strong evidence that social media is being used to both recruit and trade enslaved Yazidi and other peoples," lead author James Cockayne said.

The report says that over 5000 women, children and men from the Yazidi religious minority are thought to have been enslaved by Islamic State extremists in Iraq.

In the past year, IS fighters have used encrypted communications app Telegram and others including WhatsApp, Twitter and Threema to auction enslaved Yazidi women and launder profits, it said.