Outgoing Iraqi Prime Minister Nuri al-Maliki made an unannounced visit to the recently liberated town of Amirli on September 1.
In footage aired on state TV, Maliki praised the mainly Turkoman Shi'ite population for enduring a two-month siege by militants from the Islamic State (IS) extremist group.
Maliki vowed Iraq would become a "big grave" for the IS militants.
Kurdish Peshmerga forces, Shi'ite militias, and Iraqi government troops supported by U.S. air strikes, broke the siege of Amirli on August 31, pushing IS forces out of the district.
Reuters reported in the nearby community of Suleiman Bek, a Peshmerga commander and locals confirmed Iranian advisers were also involved in the battle for their area.
The Peshmerga commander, speaking under condition of anonymity, said, "The Iranians had a role in this. They supplied weapons and helped with the military planning."
Meanwhile, officials say Iraqi troops and Kurdish forces on September 1 retook one more town from Islamic State (IS) fighters.
Officials said Peshmerga also said they regained control of the town of Zumar.
The IS and its allies control large parts of northern and western Iraq after entering the country at the start of this year from areas in northeastern Syria.
The UN said on September 1 that at least 1,420 people were killed in Iraq in August.
Another 1,370 Iraqis were wounded and some 600,000 forced to flee as IS militants advanced into their areas.
UN representative in Iraq Nikolay Mladenov said, "Thousands continue to be targeted and killed by IS and associated armed groups simply on account of their ethnic or religious background."
IS militants have carried out mass executions in Iraq and Syria, often by decapitation.
The UN's top human rights body on September 1 approved an Iraqi government request to investigate alleged crimes against civilians committed by Islamic State (IS) militants in northern and western Iraq.
The UN Human Rights Council in Geneva unanimously agreed to a nearly $1.2 million fact-finding mission to Iraq to investigate atrocities reportedly committed by IS insurgents.
Any evidence could be used for international war-crimes prosecution.
Iraqi Human Rights Minister Muhammad Shia al-Sudani told the council before the vote that "we are facing a terrorist monster."
In Germany, Chancellor Angela Merkel, defending her government's decision to send weapons to the Peshmerga, said on September 1 that the Islamic State is a major security threat to both Germany and Europe.
In Britain, Prime Minister David Cameron addressed the House of Commons on September 1 to outline tougher measures against Britons suspected of joining jihadists in Syria and Iraq.
Cameron said he would bring in new laws to give police the power to seize the passports of would-be jihadists and stop suspected Islamist fighters from returning to Britain