The Iraqi government on Tuesday denounced a "hostile act" after U.S. airstrikes in the country killed one and injured 18 others.

U.S. claims the airstrikes targeted a pro-Iranian group in Iraq in response to dozens of reported attacks on American and allied forces in the region since the Oct. 7 outbreak of Israel's war on Gaza.

The United States has since repeatedly targeted sites used by Iran and its proxy forces in Iraq and Syria.

Iraq said the latest U.S. 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'

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

"U.S. 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 organization" by the U.S. State Department in 2009.

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