UNITED NATIONS-- Ahead of an international fundraising conference for Yemen, the United Nations has received nearly 1 billion U.S. dollars from Saudi Arabia and the United Arab Emirates (UAE), urging other donors to follow suit and help tackle the world's worst humanitarian crisis there.

UN Secretary-General Antonio Guterres expressed his deep gratitude for the 930 million dollars provided on Tuesday evening by the two donor countries to the Yemen Humanitarian Fund.

"I would like to take this occasion to appeal to all the other donors who will be meeting in Geneva next week... to follow the same generosity," the UN chief told reporters here, after meeting with Saudi Crown Prince Mohammed bin Salman Al Saud.

"These funds cover almost one-third of the $2.96 billion required to implement the 2018 Yemen Humanitarian Response Plan, which will enable the United Nations and its partners to help alleviate the suffering of millions of vulnerable people across Yemen," a statement issued by Guterres' office said, following the signing of the memorandum on the voluntary contributions.

More than 22 million people in Yemen require humanitarian aid or protection assistance, including 2 million who are internally displaced due to the ongoing conflict between the government and rebel forces.

On April 3, donors will meet in the humanitarian pledging conference in Geneva, Switzerland.

The UN chief and the Crown Prince discussed the obligations of all parties to the conflict under international humanitarian law to protect civilians and civilian infrastructure, and the critical need for humanitarian access across the country and for all of Yemen's ports to remain open to both humanitarian and commercial movement.

Separately, the UN Security Council condemned the Houthi missile attacks targeting several cities of the Kingdom of Saudi Arabia on Sunday.

In a press statement, the members of the Security Council condemned "in the strongest possible terms" the multiple Houthi missile attacks, including the use of ballistic missiles, targeting several cities of the Kingdom of Saudi Arabia, including its capital Riyadh, which threatened civilian areas and resulted in at least one fatality.

"The members of the Security Council underlined that such attacks pose a serious national security threat to the Kingdom of Saudi Arabia as well as a wider threat to regional security," it said.

They also expressed alarm at the stated intention of the Houthis to continue these attacks against Saudi Arabia, as well as to launch additional attacks against other states in the region.

"The members of the Security Council called on all Member States to fully implement all aspects of the arms embargo as required by the relevant Security Council resolutions, including resolution 2216 (2015) and in that regard expressed their grave concern at the reports of continuing violations of the arms embargo," it said.