WASHINGTON, Sept 28 (Reuters) - U.S. President Joe Biden"s national security adviser, Jake Sullivan, had a detailed discussion about the war in Yemen on Tuesday in a meeting with Saudi Crown Prince Mohammed bin Salman, a senior administration official said. The war, in which a Saudi-led coalition has been battling the Houthis, has devastated Yemen"s economy and depleted foreign exchange reserves in the impoverished Arabian Peninsula nation, which imports the bulk of its goods. Sullivan is on a trip this week to Saudi Arabia and the United Arab Emirates along with the U.S. special envoy to Yemen, Tim Lenderking and Biden Middle East envoy Brett McGurk. Sullivan met in Saudi Arabia with the crown prince as well as Deputy Defense Minister Khalid bin Salman, Interior Minister Abdulaziz bin Saud bin Nayef, National Guard Minister Abdullah bin Bandar, among others. "They had a detailed discussion of Yemen conflict, and both parties endorsed the efforts of the new UN Special Envoy to Yemen Hans Grundberg and agreed to intensify diplomatic engagement with all relevant parties. Special Envoy Lenderking will remain in the region to follow up on the detailed discussions," the official said. The United Nations has described the situation in war-torn Yemen as the world"s largest humanitarian crisis. Seven years of fighting have also plunged the nation into an economic crisis, triggering food shortages. The official also said Sullivan thanked the crown prince for "Saudi Arabia’s hospitality in permitting thousands of at-risk Afghans to transit through Saudi territory" during Biden"s chaotic withdrawal from Afghanistan last month. Sullivan will be in Cairo on Wednesday for meetings with Egyptian officials that will include a discussion on Libya, White House National Security Council spokeswoman Emily Horne said in a statement. Elections in Libya were mandated as part of a roadmap drawn up last year by a political forum convened by the United Nations to end a decade-long crisis, but disputes over the vote threaten to unravel the peace process. Libya has suffered chaos and violence since the 2011 NATO-backed uprising that ousted Muammar Gaddafi, and it was split after 2014 between warring western and eastern factions. Horne said Sullivan would also discuss Egypt’s role in promoting "security and prosperity" for Israelis and Palestinians following the visit by Israeli Prime Minister Naftali Bennet to Egypt earlier this month. Sullivan will host Israel"s national security adviser, Eyal Hulata, in Washington on Oct. 5 for more discussions, she said.