U.S. Secretary of State John Kerry praised Saudi Arabia as a "very, very important" ally on Monday as he visited the Gulf kingdom on a mission to soothe strains in the relationship over U.S. policy on Iran, Syria and the Palestinian issue.

Kerry, touring the region after a flurry of signals from the kingdom that it dislikes Washington's recent approach, met foreign minister Prince Saud al-Faisal on Monday morning and later began talks with King Abdullah.

"We have very important things to talk about to make sure the Saudi-U.S. relationship is on track, rolling forward and doing things that we need to accomplish," Kerry said in remarks to U.S. Embassy staff.

Washington's relationship with the Saudis was crucial as the region faced changes and challenges from the transition in Egypt to civil war in Syria.

"The Saudis are very, very important to all of us. The Saudis are really the senior player in the Arab world together with Egypt," he said.

Saudi Arabia, Washington's main Arab ally, is angry over what is sees as a weak foreign policy on the part of the Obama administration which has allowed Israel to continue building settlements in the Palestinian territories and conflict to persist in Syria.

Saudi concerns are also partly founded on a fear that President Barack Obama's moves to reduce tensions with Iran will give Riyadh's main regional adversary an opportunity to extend its influence in Arab countries.

Speaking before his meeting with the foreign minister, Prince Saud al-Faisal, Kerry reiterated that the United States was determined Iran would not get a nuclear weapon. Iran says it is enriching uranium only for civilian energy purposes.

Kerry's visit is his first since the Saudi intelligence chief warned last month of a "shift away" from Washington and said Riyadh's abdication of its seat on the U.N. Security Council was a message for the United States.

A senior State Department official, who requested anonymity, played down suggestions of a big rift. "We have a tremendous number of ongoing discussions, virtually on a daily basis, with senior Saudi officials," he said.

The official acknowledged that Saudi Arabia opposed Iran's participation in proposed Syria peace talks in Geneva. Riyadh is a leading supporter of the rebels fighting Syrian President Bashar al-Assad, who is a close ally of Iran.

FRUSTRATION

Abdullah al-Askar, chairman of the foreign affairs committee in Saudi Arabia's appointed quasi-parliament, the advisory Shoura Council, told Reuters he hoped Kerry would help to mend fences.

"I think he came to make a change. There are a lot of problems (and) misunderstanding between the two countries. But they have been our allies for 70 years," he said, emphasizing he was speaking in a personal capacity.

"Gulf states want to know what America means to do in going further with relations with the Iranians, which may be at the cost of Gulf states."

In the most senior levels of Saudi government, princes are also exasperated by U.S. reluctance to back Egypt's military in July after it overthrew the elected Islamist president.

"The Saudis' position will not be changed until it's proven on the ground that the U.S. is changing its policy," said Mustafa Alani, an analyst at the Gulf Research Centre in Geneva.

Saudi royals were also disappointed by Kerry's efforts in bringing about an agreement to disarm Syria's chemical arsenal in August after a gas attack in Damascus, Alani said.

"They want a clear commitment from the American side that Geneva 2 (peace talks) will not turn into 3, 4 and 5. And if this process fails to achieve the objective of removing Assad from power, the Americans should change their policy from diplomacy to changing the balance on the ground," he said.

The U.S. official said Kerry would make clear to the Saudis that Iran would not be welcome at Syria peace talks in Geneva unless it backed a past agreement under which Assad gave up power. "Iran has not done that, and without that even we couldn't consider the possibility of their participating."

On ending the stalemate with Tehran over its nuclear program, the official said: "We frankly completely agree with the Saudis about their concerns."

In addition to Riyadh, Jerusalem and Bethlehem, Kerry will make stops in Jordan, the United Arab Emirates, Algeria and Morocco.