A statement from the Yazidi Progress Party said 300 captives were killed on Friday in the Tal Afar district near the city, BBC reports.

Iraqi Vice-President Osama al-Nujaifi described the reported deaths as "horrific and barbaric".
Thousands of members of the religious minority group were captured last year.

It is not clear how they were killed, or why this has happened now, says the BBC's Middle East editor Alan Johnston.

Many are reported to have been held in Mosul, the main stronghold of ISIS after the militants swept through large areas of northern and western Iraq, and eastern Syria in 2014.

Yazidis, whose religion includes elements of several faiths, are considered infidels by ISIS.

Thousands fled to the Kurdish-controlled region of northern Iraq after ISIS captured the Yazidi-populated Sinjar district in Nineveh province.

Hundreds of men were killed, while some Yazidi women were held and used as sex slaves.
The Yazidi Progress Party's statement, quoted by the Shafaq News website, condemned the latest incident as a "heinous crime" and called on Iraqi forces to free those still held by ISIS.

In January, ISIS released some 200 mainly elderly Yazidis into the hands of Kurdish officials near the city of Kirkuk.

Many of them, held in Mosul, had disabilities or were wounded, though no reason was given by ISIS for their release.

In recent months, ISIS has been pushed back from some of the areas it captured, though many Yazidi villages are thought to remain under the militants' control.

In December, Kurdish Peshmerga forces drove back ISIS militants in north-western Iraq, relieving a long siege of Sinjar Mountain where thousands of Yazidis had sought refuge.

The Iraqi government forces also declared it had taken back control of the city of Tikrit in April.