US President Barack Obama is to sign an order imposing sanctions on three top Syrian officials, Syria’s intelligence agency and Iran’s Revolutionary Guard.
The sanctions freeze any assets the groups have in US jurisdictions and bar Americans from business with them.
Mr Obama authorised the penalties in the wake of a bloody crackdown on anti-government dissent that has left some 500 people dead, US officials said.
The names of the Syrian officials targeted have not yet been revealed.
Thousands of protesters took to the streets of the Syrian capital Damascus and around the country on Friday, in protest against the regime of President Bashar al-Assad.
Witnesses said troops opened fire on demonstrators in the city of Deraa, where the unrest began in mid-March, reportedly killing 15 people.
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US sanctions target Syria assets