DUBAI — Iranian forces have launched war games in an area near the border with Iraq's Kurdistan region, Iran's state media reported on Sunday, a day before an independence referendum is to be held in the region.

State broadcaster IRIB said the exercises, part of annual events held in Iran to mark the beginning of the 1980-1988 war with Iraq, are centered in the Oshnavieh border region.

The war games will include artillery, armored and airborne units, IRIB reported.

Clashes with Iranian Kurdish militant groups based in Iraq are fairly common in the border area.

Iran has joined Turkey and the Iraqi government in voicing opposition to the referendum.

Iran's Revolutionary Guard's website did not say how long the drill will last, only that airborne and missile units will participate in the exercise.

Meanwhile, the US embassy in Iraq cautioned its citizens that there may be unrest during a referendum on independence planned by the Kurdish authorities in northern Iraq, opposed by the central government in Baghdad.

"In particular, US citizens should avoid travel into and within territories disputed between the Kurdish Regional Government (KRG) and the Government of Iraq," the travel warning said.

The KRG has resisted calls by the United Nations, the United States and Britain to delay the referendum. Iraq's powerful neighbors, Iran and Turkey, strongly oppose the vote as they fear could fuel separatism among their own Kurds.

The Kurds have been a close American ally for decades, and the first US air strikes in the campaign against Daesh (the so-called IS) were launched to protect Irbil. Kurdish forces later regrouped and played a major role in driving the extremists from much of northern Iraq, including Mosul, the country's second largest city.

"The Kurdish contribution to the ISIS fight, it can't be overstated," said US Army Col. Charles Costanza, a commander at a coalition base just outside Irbil, using another acronym for the extremist group. "We couldn't have done Mosul without the Kurds."

But the US has long been opposed to Kurdish moves toward independence, fearing it could lead to the breakup of Iraq and bring even more instability to an already volatile Middle East.

The Kurds' sense of sacrifice and betrayal is rooted in decades of war and oppression, in which they repeatedly rose up against the Baghdad government and were often brutally repressed.

During the Iran-Iraq war in the 1980s, the Kurds sided with Iran against Saddam Hussein, who punished them with a scorched-earth campaign involving chemical weapons that killed an estimated 50,000 people. A no-fly zone imposed by the US in the early 1990s largely halted the killings, and allowed the Kurds to develop de facto autonomy, which was formalized after the 2003 US-led invasion.

In the years after the American invasion, the Kurdish region emerged as a rare success story. The peshmerga insulated the region from the insurgency and sectarian killings that plagued much of the rest Iraq, and oil revenues fueled an economic boom.

That all changed in 2014, when IS rampaged across northern Iraq, at one point approaching within a few miles of Irbil. The collapse in global oil prices later that year led to a severe economic downturn, exposing a government riddled with corruption and an economy dominated by a bloated public sector. — Agencies