The United Nations Security Council condemned missile attacks on Saudi Arabia launched by Yemen's Houthi rebels last weekend and expressed "grave concern" at reports the Houthis obtained the weapons in violation of a UN arms embargo.

In a statement issued late on March 28, the 15-member council -- including Russia, China, and top Western powers -- said it condemned the missile attacks "in the strongest possible terms" and said they pose a threat to regional security.

The council also "expressed alarm" that the Houthis are threatening to continue attacking Saudi Arabia, which has accused Iran of supplying the ballistic missiles used by the Houthis. Tehran has denied the allegation.

"The members of the Security Council expressed their grave concern at the continued deterioration of the humanitarian situation in Yemen and the devastating humanitarian impact of the conflict on civilians," the statement said.

The council statement did not name who is violating the arms embargo against the Houthis. But independent UN experts concluded in January that Iran had manufactured the missiles used in a series of similar missile attacks by the Houthis last year and Tehran violated the arms embargo because it failed to prevent those missiles from getting into Houthi hands.

Despite the UN conclusions, last month Russia used its veto power in the council to block a western resolution call outing Tehran for violating the arms embargo.

The United States in particular has been pushing to hold Iran accountable for allegedly supplying missiles and drones to the Houthis.

The latest Houthi missile attacks on March 25 were the most extensive and deadly so far. Saudi forces said they shot down three missiles over Riyadh, with debris falling on a home in the capital, killing an Egyptian laborer and wounding two others.

The Saudis said air defenses repelled missiles fired at three southern cities -- Najran, Jizan, and Khamis Mushait.

On March 26, the Saudi-led bombing coalition displayed what it said was fragments from the missiles at a news conference in Riyadh and said they showed the weapons were made in Iran.

A coalition spokesman said it was "reserving the right" to respond against Iran at an "appropriate" time.

Iran's Islamic Revolutionary Guards Corps a day later denied providing the weapons to the Houthis and accused the Saudis of blaming Iran in an effort to distract from what it said were "atrocities" committed by Riyadh in Yemen.

A Saudi-led blockade of Yemeni ports last year threatened to worsen what the United Nations has called the world's worst humanitarian crisis, with millions of Yemenis living on the verge of famine and ravaged by diseases such as cholera often without medical supplies.

An international outcry about the dire conditions for civilians in Yemen prompted Saudi Crown Prince Mohammed bin Salman to present a $930 million check to UN Secretary-General Antonio Guterres for humanitarian aid to Yemen on a visit to the UN on March 28.

Guterres thanked the prince, but stressed that a political solution was needed to end the war in Yemen, not just a humanitarian response.

Were the Saudis to make good on their veiled threat to retaliate against Iran, it could sharply escalate a three-year conflict that has widely been viewed as a proxy war between regional rivals Iran and Saudi Arabia.

With reporting by AFP and Reuters