WASHINGTON, Jan. 11 (Xinhuanet) -- The United States claimed on Wednesday that Syria had been blocking the inquiry into the killing of former Lebanese prime minister Rafiq Hariri and threatened to take the issue to the United Nations for action.

    "Syria must cease obstructing the investigation into the assassination of former Lebanese prime minister Hariri and instead cooperate fully and unconditionally, as required by UN Security Council resolutions," US Secretary of State Condoleezza Rice said in a statement.

    "We call upon the Syrian regime to respond positively to the requests of UN Independent International Investigation (UNIIIC). We intend to refer this matter back to the Security Council if Syrian obstruction continues," Rice said, adding that the United States has "grave and continuing concerns about Syria's destabilizing behavior and sponsorship of terrorism."

    The United States has been accusing Syria of blocking the investigation to the murder case of Hariri. Syria has denied it has any links to the killing of Hariri. Enditem