Trump threatens Turkey with 'significant sanctions' over Syria offensive

US President Donald Trump is ready to authorise wide-ranging sanctions on Turkey aimed at dissuading Ankara from further military action in north-eastern Syria, Treasury Secretary Steven Mnuchin said Friday.

Addressing reporters at the White House, Mnuchin said Trump was poised to sign an executive order approving "very significant new sanctions authorities" - but that the United States was not yet "activating" the measures.

"These are very powerful sanctions. We hope we don't have to use them but we can shut down the Turkish economy if we need to," Mnuchin said.

The punitive measures, Mnuchin said, can be targeted at any person associated with the Turkish government.

The sanctions announcement came hours after the Pentagon blasted Turkey for its three-day old assault on Kurdish-led forces in northeast Syria, warning of "serious consequences" for Ankara in the strongest US statement yet against an assault that Trump had initially appeared to green light.

Read more: What happens next? Turkey launches a new offensive in Syria

"The president is concerned about the ongoing military offensive, and potential targeting of civilians, civilian infrastructure, ethnic or religious minorities," Mnuchin said.

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"Also the president wants to make very clear it is imperative that Turkey not allow even a single ISIS fighter to escape."

A statement from the Treasury said Trump's executive order would give it the "authority to designate individuals and entities of the Government of Turkey involved in human rights abuses or actions leading to the further deterioration of peace, security, and stability in northeastern Syria."

"At the direction of President Trump we will be targeting specific Turkish individuals or departments as needed," Mnuchin was quoted as saying.

"This is a notice to banks and other parties to be on notice of potential actions.”

The Turkish military offensive, now in its third day, has left dozens of fighters and civilians dead and sent 100,000 people fleeing their homes, according to a UN estimate.

Agencies contributed to this report.