Amnesty International says it has new evidence Islamic State militants are carrying out "a wave of ethnic cleansing" against minorities in northern Iraq.

The human rights group said IS had turned the region into "blood-soaked killing fields".

Earlier, Iraqi Shia militias and Kurdish forces broke a two-month siege by IS fighters in the town of Amerli.

IS and allied Sunni rebels have seized large swathes of Iraq and Syria.

Thousands of people have been killed, the majority of them civilians, and more than a million have been forced to flee their homes in recent months.

Amnesty says it has gathered proof that several mass killings took place in the northern region of Sinjar in August. Two of the deadliest took place when IS fighters raided villages and killed hundreds on 3 August and 15 August.

"Groups of men and boys including children as young as 12 from both villages were seized by IS militants, taken away and shot," the UK-based group said.

"IS is carrying out despicable crimes and has transformed rural areas of Sinjar into blood-soaked killing fields in its brutal campaign to obliterate all trace of non-Arabs and non-Sunni Muslims."

On Monday, the United Nations announced it was sending a team to Iraq to investigate "acts of inhumanity on an unimaginable scale".

Deputy Human Rights Commissioner Flavia Pansieri warned that IS (formerly known as Isis) was targeting Christian, Yazidi, Turkmen, Shabak, Kaka'i, Sabean and Shia communities "through particularly brutal persecution".

(BBC)