The United States has repeatedly targeted sites used by Iran and its proxy forces in Iraq and Syria in response to dozens of attacks on American and allied forces in the region since the October 7 outbreak of the war.

Iraq said the latest US strikes killed one member of the security forces and wounded 18 other people, including civilians.

In a statement, it warned that such attacks "infringe upon Iraq's sovereignty and are deemed unacceptable under any circumstances or justification".

"Iraqi military sites were targeted by the American side justifying the act as a response," the Iraqi government said, adding it "resulted in the martyrdom of one service member and the injury of 18 others, including civilians".

"This constitutes a clear hostile act.

"It runs counter to the pursuit of enduring mutual interests in establishing security and stability, and it opposes the declared intention of the American side to enhance relations with Iraq."

Questioned by AFP, an official in Iraq's interior ministry said a strike had targeted a Hashed al-Shaabi site in Hilla, the capital of Babylon province.

One person was killed and 20 others wounded, the official said, giving a higher injured toll than the government.

Four others were wounded in a second strike in Wassit province. The casualty toll was confirmed by security sources in both Babylon and Wassit provinces.

- 'Proportionate strikes' -

US Defense Secretary Lloyd Austin said earlier American forces had carried out strikes on three sites used by pro-Iran groups in Iraq in response to a series of attacks on US personnel.

"US military forces conducted necessary and proportionate strikes on three facilities used by Kataeb Hezbollah and affiliated groups in Iraq," Austin said in a statement.

The Iran-backed Kataeb Hezbollah, or Hezbollah Brigades, forms part of the Hashed al-Shaabi, a coalition of former paramilitary forces that are now integrated into Iraq's regular armed forces.

The group was designated a "terrorist organisation" by the US State Department in 2009.

"These precision strikes are a response to a series of attacks against US personnel in Iraq and Syria by Iranian-sponsored militias, including an attack by Iran-affiliated Kataeb Hezbollah and affiliated groups on Arbil Air Base" on Monday, Austin said.

That attack wounded three US military personnel, one critically, US National Security Council spokesperson Adrienne Watson said.

US President Joe Biden was briefed on the attack -- which was carried out with a one-way attack drone -- and directed the US strikes in a call with Austin and other national security officials after ordering the defense department to prepare a response, the statement said.

Biden "places no higher priority than the protection of American personnel serving in harm's way. The United States will act at a time and in a manner of our choosing should these attacks continue," the statement added.

The drone attack was claimed by the Islamic Resistance in Iraq, a loose formation of armed groups affiliated with the Hashed al-Shaabi.

A tally by US military officials has counted 103 attacks against its troops in Iraq and Syria since October 17, most of which have been claimed by the Islamic Resistance in Iraq, which opposes US support for Israel in its war against Hamas in the Gaza Strip.

The United States has about 2,500 soldiers deployed in Iraq and around 900 in Syria, as part of efforts to prevent a resurgence of the jihadist Islamic State group.