An Iraqi military source told Reuters that Hashd al-Shaabi militias were targeted near Taji military base, six people were killed and three were seriously injured.

Hashd al-Shaabi said that a medics convoy was hit in the air strike but no senior members was killed or wounded. 

Hashd al-Shaabi said in a written statement: "A health convoy belonging to Hashd al-Shaabi was hit near the Taji stadium in Baghdad."

Iraqi state television had said they were U.S. air strikes. However, the U.S.-led coalition fighting Islamic State said early on Saturday it did not conduct any air strikes near Camp Taji north of Baghdad, writes Reuters.

The day before this attack, the US killed top Iranian general Qassem Suleimani and prominent Hashd al-Shaabi commander in Baghdad.

This attack caused new concerns in the Middle East for the consequence that it may have.

While voices of vengeance rose from Iran, US President Donald Trump argued that he acted to prevent a war rather than to start one.

Trump claimed that Suleimani - who he called "number one terrorist" - was planning an attack on American diplomats and soldiers.