By Angus McDowall
RIYADH, Oct 18 (Reuters) - Saudi Arabia turned down a coveted seat on the United Nations Security Council on Friday in a rare display of anger at the failure of the international community to end the war in Syria and act on other Middle East issues.
The kingdom condemned what it called international double standards on the Middle East and demanded reforms in the Security Council, which has been at odds on ways to end the fighting in Syria.
Unlike in the past, when Riyadh's frustration was mostly directed at Russia and China, it is now also aimed at Washington, its oldest international ally, which has pursued policies since the Arab Spring that Saudi rulers have bitterly opposed.
Citing the Security Council's failure to resolve the Israeli-Palestinian dispute, take steps to end Syria's civil war and stop nuclear proliferation in the region, Riyadh said the body had instead perpetuated conflicts and grievances.
"Saudi Arabia ... is refraining from taking membership of the U.N. Security Council until it has reformed so it can effectively and practically perform its duties and discharge its responsibilities in maintaining international security and peace," said a Foreign Ministry statement.
A founding member of the United Nations, Saudi Arabia was one of five countries elected by the body's General Assembly on Thursday to serve a two-year term on the 15-member Security Council.
The council, which has power to authorise military action, impose sanctions and set up peacekeeping operations, has 10 rotating members. The United States, China, Russia, France and Britain are permanent members, which wield a veto.
U.N. Secretary-General Ban Ki-moon said he had not received any official notification from Saudi Arabia rejecting its first-ever seat on the council.
A decision of such magnitude would have to have been taken by King Abdullah or Crown Prince Salman, said a Saudi analyst who asked not to be identified.
"Saudi Arabia has been working on (the council seat) for the last three years. They trained diplomats, male and female, the cream of the Foreign Ministry, our best talented youths. Then somebody made the decision suddenly to pull out," he said.
In a single previous example of a council member walking away from the body, the Soviet Union in 1950 boycotted its permanent seat for half a year in protest at Taiwan's occupation of the Chinese place instead of Beijing.
The Russian Foreign Ministry said it was surprised at Saudi Arabia's move and puzzled by its accusations against the Security Council. "With its decision, Saudi Arabia has removed itself from the collective work of the U.N. Security Council to support international peace and security," the ministry said.
The conservative Islamic kingdom has traditionally avoided big political statements, preferring to wield its influence as the world's top oil exporter, birthplace of Islam and chief Arab ally of the United States behind closed doors.
However, immersed in what they see as a pivotal struggle for the future of the Middle East with arch rival Iran, Saudi rulers are furious that the United Nations has taken no action over the Syrian conflict where they and Tehran back opposing sides.
Russia and China have repeatedly blocked resolutions supported by Saudi Arabia to toughen action against Syrian President Bashar al-Assad, whose forces' assault on rebel-held areas has been described by the kingdom as genocide.
In a sign of mounting Saudi anger, Foreign Minister Prince Saud al-Faisal cancelled his speech at the U.N. General Assembly two weeks ago in what a diplomatic source said was a response to international inaction on Middle East issues.
France, a Security Council permanent member, said it understood Saudi concerns. "We think that Saudi Arabia would have brought a very positive contribution to the Security Council but we also understand the frustration of Saudi Arabia," French U.N. Ambassador Gerard Araud said.
A U.S. official would not comment on the Saudi decision but praised the council's "vital work."
Blood-drenched images of Syria's civil war, in which more than 100,000 have died and in which millions have been displaced, are aired daily on Saudi news and the kingdom has backed the rebels with arms and money.
Saudi anger boiled over after Assad escaped U.S.-led military strikes in response to a poison gas attack in Damascus by agreeing to give up his chemical arsenal.
"There are people being killed every day, every hour. And the Muslim world is very angry because we don't see any action or any strong stance from the Security Council towards this situation," said Abdullah al-Askar, foreign affairs committee chairman in the kingdom's quasi-parliament, the Shoura Council.
The Security Council has been split on how to handle the civil war in Syria, with Western powers pushing for stronger sanctions and Russia vetoing resolutions to that end.
Saudi concerns that the U.S. decision to avoid strikes demonstrated weakness were underscored by signs of a tentative reconciliation between Washington and Tehran, something Riyadh fears may lead to a "grand bargain" on Iran's nuclear programme that leaves Gulf Arab states at a disadvantage.
It has been sharply critical of U.S. policy in the Middle East since the Arab Spring, not only on Syria but also in Egypt, where Washington cut off aid to the military after it ousted a Muslim Brotherhood government that Riyadh saw as a threat.
Russia said it hoped Asian countries would swiftly select another candidate in place of Saudi Arabia for election to the council, but it was not clear whether such a procedure would be widely accepted given the lack of historical precedent.
U.N. Security Council reform has long been a topic of debate. Some countries want the council expanded, while Germany, India, Brazil and Japan are pushing to become permanent members.
"Membership in the Security Council is a decision by member states," Ban said. "I encourage all member states to fully engage with the principal organs of the United Nations while advancing their efforts to improve their working methods."
Alongside its anger over inaction on Syria, Saudi Arabia also cited the proliferation of weapons of mass destruction and the failure to resolve the Palestinian crisis as reasons for declining its first ever seat on the Security Council.
The Saudis have expressed disappointment at U.S. President Barack Obama's failure to push Israel to end settlement building in the West Bank and agree to a Palestinian state.
The reference to proliferation appeared aimed at both Iran, which Western and Gulf Arab states fear is using a civilian nuclear programme as cover to develop atomic weapons, and at Israel, which has long been believed to possess a nuclear bomb.
Iran denies it is seeking atomic weapons capability. Israel has never commented on accusations it has the bomb.
Riyadh has previously pressed Washington to "cut off the head of the snake" by striking Iranian nuclear facilities.
Asked about the Saudi concerns, Guatemalan U.N. Ambassador Gert Rosenthal, currently a council member, said: "They should have thought of that before competing for the seat."