Yemen was already the poorest country in the Arab world, but this year's war has created what a UN envoy has called a "catastrophic" situation where up to 80 percent of people need humanitarian aid.
Leaders from the six Gulf Cooperation Council states, gathered in Riyadh for a two-day summit, talked of "preparing an international conference on the reconstruction of Yemen" after a political solution to the conflict, a statement said.
Leaders from the oil and gas-rich Gulf -- Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates -- spoke of "a plan to rehabilitate the Yemeni economy to integrate it into the Gulf economy."
Their statement comes less than a week before long-awaited UN-led peace talks between Yemen's warring sides begin on Tuesday in Switzerland.
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Gulf leaders welcomed next week's talks, but said any settlement must unconditionally be based on April's UN Security Council Resolution 2216, which calls for rebels to withdraw from Yemen's key cities and surrender their weapons.
A Saudi-led coalition launched air strikes in Yemen in late March to support forces loyal to President Abedrabbo Mansour Hadi after Iran-backed Huthi rebels overran much of the country.
The United Nations says more than 5,700 people have been killed in Yemen, about half of them civilians, since March when fighting intensified.
Human rights groups have criticised both the rebels and the coalition over the loss of civilian lives.