US President Barack Obama meets with Crown Prince Mohammed bin Nayef of Saudi Arabia in the Oval Office of the White House in Washington May 13, 2015. [Photo/Agencies]

WASHINGTON - Obama met with Saudi Arabia's Crown Prince Mohammed bin Nayef and Deputy Crown Prince Mohammed bin Salman at the White House and went out of his way to play down the absence of Saudi King Salman from a summit.

"The United States and Saudi Arabia have an extraordinary friendship and relationship that dates back to (President) Franklin Roosevelt," Obama said at the start of the meeting. "We are continuing to build that relationship during a very challenging time," he said.

King Salman decided abruptly to skip the White House meeting and a summit of the Gulf Cooperation Council at the president's Camp David retreat in Maryland outside Washington on Thursday.

Obama said he and the Saudi leaders would discuss how to build on a ceasefire in Yemen and work toward "an inclusive, legitimate government" in Saudi Arabia's impoverished neighbor, where a Saudi-led coalition has been bombing Houthi rebels.

They also discussed efforts to counter Islamic State militants and cooperate to resolve conflicts in Iraq, Syria and Yemen, she said.

White House Josh Earnest said King Salman had not expressed any specific concerns about the agenda at Camp David when he met Secretary of State John Kerry in Riyadh last week, and added it was unprecedented that two high profile Saudi leaders were attending.