The United States on Thursday announced sanctions against 18 senior regime officials linked to chemical attacks in the war-torn country.

The US Department of the Treasury said it took the action in response to reports by the Organization for the Prohibition of Chemical Weapons (OPCW) that the Assad regime had used chlorine in attacks against opposition-controlled areas.

The sanctions freeze any property or interest in property of the identified persons and generally prohibits financial transactions with US individuals.

"The regime's use of chemical weapons against its own people is a heinous act that violates the longstanding global norm against the production and use of chemical weapons," Adam J Szubin, an acting under secretary for Terrorism and Financial Intelligence, said.

Last year, OPCW blamed Assad regime for three chlorine gas attacks unleashed in three different areas of the country in April 2014 and March 2015.