The United States on Wednesday denounced the "genocide" carried out by the Islamic State group against Christians, Shias and Yazidis, as the State Department unveiled its somber annual report on religious freedom around the world.

The IS group "continued to pursue a brutal strategy of what Secretary (John) Kerry judged to constitute genocide against Yazidis, Christians, Shias, and other vulnerable groups in the territory it controlled," the State Department said, in its comprehensive look at the situation in more than 200 countries in 2015.

Kerry and United Nations experts had previously used the term "genocide" to refer to crimes carried out by IS jihadists in Iraq and Syria.