BAGHDAD, Jan. 4 (Xinhua) -- A convoy of Iraq's Popular Mobilization Forces was attacked early Saturday in northern Baghdad, the paramilitary group confirmed in a statement.

"The attack, which took place near the Taji Stadium in Baghdad, hit a medical convoy of the Popular Mobilization Forces," said the group, which is also known as Hashd Shaabi in Arabic.

It added in the statement that no senior members were affected, refuting earlier reports that said its senior officials were killed in the attack.

Reports said that six people were killed and three others injured after two of the three cars in the convoy were found burned. Previously at least five deaths were reported.

The new airstrike took place about 24 hours after a U.S. drone attack near Baghdad International Airport killed Qasem Soleimani, commander of the Quds Force of Iran's Islamic Revolutionary Guard Corps, and Iraqi militia commander Abu Mahdi al-Muhandis, who was the deputy chief of the pro-Iran Hashd Shaabi forces.

Iran's top leader Ayatollah Ali Khamenei and Iranian President Hassan Rouhani have vowed to retaliate against the United States for Soleimani's death.

Till press time, it is not clear who is responsible for the fresh attack, but Iraqi state television reported that the United States was behind the strike. There was no comment from Washington yet.

Pentagon has announced that the attack killing Soleimani was conducted under U.S. President Donald Trump's direction as a "defensive action" as the Iranian senior military leader was accused of planning further attacks on U.S. diplomats and service members in Iraq.

On Tuesday, Iraqi protesters stormed the U.S. embassy compound in Baghdad to protest the U.S. air raids conducted on Sunday against five bases of Iran-backed militias in Iraq and Syria. On Sunday evening, U.S. forces bombarded the headquarters of Hashd Shaabi's 45th and 46th Brigades, killing 25 and injuring 51.  ■