US Secretary of State John Kerry said on Thursday that the so-called Islamic State has committed genocide against Christians and other minority groups in the Middle East.

In a press conference at the State Department, Mr Kerry said that in his judgement, Daesh (another term for the Islamic State which is also known as ISIS) is "responsible for genocide against groups in areas under its control including Yezidis, Christians, and Shiite Muslims".

"Daesh is genocidal by self-proclamation, by ideology, and by its actions - in what it says, what it believes and what it does," he said.

By way of example, Mr Kerry said in August, 2014, members of IS had killed hundreds of Yezidi men and older women and trapped tens of thousands at Mt Sinjar and that while rescue efforts had "saved many", IS still "captured and enslaved" thousands of Yezidi girls and women, "selling them at auction, raping them at will, and destroying the communities they had lived in for countless generations".

He said IS had also killed Christians "because they are Christians, Yezidis because they are Yezidis, Shia because they are Shia".

The statement comes after a unanimous vote in the US House of Representatives earlier this week in which members said atrocities committed by ISIS in Iraq and Syria to "constitute war crimes, crimes against humanity, and genocide".

It is reportedly the first time the US has officially declared a genocide since that in Darfur in 2004 and while it doesn't legally obligate any particular action, it adds to the pressure on the Obama administration to take more aggressive action to tackle IS and to those advocating for a more inviting refugee program.

The move follows that of the European Parliament in February, when it officially declared Islamic State's campaign to be genocide.