Remnants of four ballistic missiles fired into Saudi Arabia by Yemen's Houthi rebels this year appear to have been designed and manufactured by Riyadh's regional rival Iran, a confidential report by United Nations sanctions monitors said, bolstering a push by the United States to punish the Tehran government.

The independent panel of U.N. monitors, in a Nov. 24 report to the Security Council seen by Reuters on Thursday, said it "as yet has no evidence as to the identity of the broker or supplier" of the missiles, which were likely shipped to the Houthis in violation of a targeted U.N. arms embargo imposed in April 2015.

Earlier this month, U.S. Ambassador to the United Nations Nikki Haley accused Iran of supplying Houthi rebels with a missile that was fired into Saudi Arabia in July and called for the United Nations to hold Tehran accountable for violating two U.N. Security Council resolutions.