In a report titled "On vulnerable ground: violence against minority communities in Nineveh province's disputed territories," the group said the area's ruling Kurds risk creating "a full-blown human rights catastrophe" for small communities that have lived there through the ages.

At issue is the status of the disputed territories immediately south of the Kurdistan regional government's region, which were "Arabised" by the government of Saddam Hussein, expelling hundreds of thousands of Kurds and minorities such as Assyrian and Chaldean Christians, Turkmens, Yazidis and Shabaks.

Iraq's disputed provinces include Nineveh, of which Mosul is the capital, the oil-rich province and city of Kirkuk, and Diyala.

The HRW report said that while Iraq's Kurds deserved redress for the crimes, including genocide, committed against them by previous governments, the issue of disputed territories should be treated separately.

"The minority communities who live there (are) in a precarious position, bearing the brunt of the conflict and coming under intense pressure to declare their loyalty to one side or the other, or face the consequences," it said.

"They have been victimised by Kurdish authorities' heavy-handed tactics, including arbitrary arrests and detentions, and intimidation, directed at anyone resistant to Kurdish expansionist plans."

The Kurdish push into the area has in turn created an opening for Sunni Arab extremists who "continue their campaign of killing minorities, especially religious minorities," the report said.

To avert the crisis, New York-based HRW said the regional government should "initiate independent and impartial investigations of individuals, including Kurdish security forces, alleged to be responsible for carrying out killings, beatings and torture against minorities."

It should also modify its constitution to give legal recognition to Shabaks and Yazidis as distinct ethnic groups and "cease repression" of those "that oppose Kurdish policies in the disputed areas," the report said.