Washington - US President Donald Trump on Friday imposed additional sanctions on Iran in retaliation for Tehran's missile attack on US forces in Iraq.

"I have issued an Executive Order authorizing the imposition of sanctions against any individual or entity operating in the construction, manufacturing, textiles, or mining sectors of the Iranian economy or anyone assisting those who engage in this sanctioned conduct," Trump said in a statement.

"This order will have a major impact on the Iranian economy, authorizing powerful secondary sanctions on foreign financial institutions," the president added.

Trump also called Iran "the world's leading sponsor of terrorism."

Treasury Secretary Steven Mnuchin earlier told reporters at a White House briefing that the measures included 17 sanctions against Iran's largest steel and iron manufacturers, as well as eight senior Iranian officials involved in "destabilizing" activities and Tuesday's missile strike.

Secretary of State Mike Pompeo said the sanctions, initially announced by Trump on Wednesday, would "deprive the regime of billions in revenue."

"As long as Iran's outlaw ways continue we will continue to impose sanctions," Pompeo added.

The president's Wednesday announcement came after Tehran fired missiles at Iraqi bases hosting US troops in retaliation for Washington's targeted killing of top Iranian General Qassem Soleimani last week.

Trump has justified the assassination by saying Soleimani was planning "imminent and sinister attacks" on US personnel, but has drawn criticism for failing to produce evidence of such attacks.

On Friday, Pompeo echoed Trump's Thursday claim that Soleimani was "looking to blow up our embassy" in Baghdad.

"We had specific information on an imminent threat," the secretary of state said.

Tensions between Washington and Tehran have steadily escalated since Trump pulled out of the Iran nuclear deal and started a "maximum pressure" campaign of reimposing sanctions against Iran.

Fears of a new war in the Middle East flared after Soleimani's killing and Iran's retaliatory strike on US forces, followed by threats by Iranian leaders that the US risked a "dangerous response" if it tried any further interventions in the region.

The new sanctions on Iran came after both sides appeared to have stepped back from the brink of war.

On Thursday, Iran's ambassador to the United Nations, Majid Takht Ravanchi, accused Washington of "economic terrorism" against his country in a statement to the Security Council.

dpa