Ambassador Samantha Power
Ambassador Samantha PowerReuters

U.S. Ambassador to the United Nations Samantha Power said on Thursday that the United States is concerned that the most dangerous terrorist groups could get a hold of chemical weapons if Syria is hiding any stockpiles.

Power spoke to reporters after the Security Council received a briefing from Sigrid Kaag, who heads the international effort to rid Syria of its chemical weapons, according to The Associated Press (AP).

If President Bashar Al-Assad is hiding any stockpiles, Power said they could fall into the hands of "extremist groups who have committed some of the most vile acts in the last few days."

Syria signed up to an international plan to destroy its chemical stockpile after the outcry that followed chemical attacks by the Damascus regime in August last year that may have killed as many as 1,400 people.

U.S. President Barack Obama recently announced that Syria's declared chemical weapons stockpile was eliminated, declaring this an important achievement against the spread of dangerous weapons of mass destruction.

He also warned that Syria's government now must follow through on pledges to destroy its remaining weapons production facilities.

Obama also said concerns about omissions and discrepancies in Syria's declaration to the Organization for the Prohibition of Chemical Weapons, the group that oversaw destruction of the weapons, must be addressed.

The civil war in Syria includes, in addition to Western-backed rebel groups that are considered “moderate”, also jihadist groups such as the Islamic State and the Al-Nusra Front, the leader of which has pledged allegiance to Al-Qaeda.