The reports quoting two Kurdish officials and a Yazidi lawmaker said insurgents from the group "Islamic State" (IS) had carried out a massacre on some 80 ethnic Yazidis in a northern Iraq village.
Men from the village were said to have been killed after IS fighters tried for days to persuade them to convert to Islam. One report said female residents were kidnapped.
Yazidi parliamentarian Mahama Khalil said he had spoken to villagers who had survived the attack. They said the killings took place during a one-hour period.
Accounts of the incident have not been independently confirmed.
A recent push by IS militants through northwestern Iraq toward Iraq's autonomous Kurdish region has sent tens of thousands of Yazidis and Christians fleeing.
Since June, large swaths of oil-rich territory in eastern Syria and northwestern Iraq have been captured by the group.
The US, which began air strikes on August 8, said it carried out more raids on Friday after receiving reports that IS "terrorists were attacking civilians."
The air strikes are the first since American troops pulled out of Iraq in 2011. US President Barrack Obama has ruled out the use of US troops on the ground.
In another international move to combat the IS advance, the UN Security Council on Friday passed a resolution cutting off funding and the flow of foreign fighters to the group. The British-drafted measure placed six Islamist leaders -- from Kuwait, Saudi Arabia and other nations -- on a sanctions list, which provides for a travel ban and assets freeze.
European foreign ministers also agreed at a meeting in Brussels on Friday to back the arming of Iraqi Kurdish fighters. Last week, the IS militants advanced to within 35 kilometers (20 miles) of Irbil before being deterred by the air strikes.
German Foreign Minister Frank-Walter Steinmeier has arrived in Iraq to assess the situation.
"We must be concerned that even the last anchors of stability here in Iraq could collapse," Steinmeier said on Saturday, shortly after arriving in the Iraqi capital, Baghdad.
Steinmeier said, however, that current steps in Iraq to form a new coalition following the resignation of Prime Minister Nuri al-Maliki offered a "ray of hope."
He said that "great hopes" were being placed in the prime minister-designate Haidar al-Abadi that he could be "the person to embody the different regions and religions in a joint government."
This was the only way to allay the widespread dissatisfaction in Iraq that was fueling support for the IS militants, Steinmeier said, describing the insurgency as a "catastrophe" in which "a murderous band of terrorists was trying to bring the country under its control."
Maliki's resignation on Thursday broke a political deadlock in Iraq. He had been accused of discriminating against the Sunni minority in Iraq, thus increasing their sympathy with the IS rebels, who also belong to the Sunni sect of Islam.
Al-Abadi has said he intends to introduce policies fostering national unity.
Steinmeier has met with al-Abadi in Baghdad (photo above). He was to travel on later to the Kurdish regional capital, Irbil, where he was scheduled to hold talks with the president of the autonomous region, Massud Barzani. The talks were to focus on how Germany can best help support the fight against IS and provide aid to the thousands of refugees in the country.
The visit by the German minister comes shortly after the first German transport plane carrying aid for people displaced by the IS advances landed in Irbil.
tj/ipj (Reuters, AFP, dpa)