The Obama administration has sought to limit any damage to the long-standing US alliance with Saudi Arabia in a rift over America's role in the Middle East that has underscored growing strategic differences.

A spate of unusually public complaints from leading members of the Saudi ruling family has shed new light on the kingdom's frustration with the United States over its perceived inaction on Syria, its diplomatic engagement with Iran and its coldness toward the military government in Egypt.

While no one is expecting a rupture in a strategic relationship that has served for more than half a century as a pillar of US policy in the region, some of the mutual interests that brought the two allies together have started to fray.

A Saudi warning that it is considering a "major shift" away from the US caught the Obama administration by surprise but it did not set off alarm bells in Washington. The White House has shown an increased willingness to risk strains with allies in order to pursue US goals of avoiding military intervention in Syria and seeking a nuclear deal with Iran, Saudi Arabia's chief rival.

US officials have taken pains to avoid the impression that they are not taking the Saudi concerns seriously.

But they are also showing no signs of giving ground, despite the warning by the Saudi intelligence chief to European diplomats earlier this week that Riyadh was contemplating a shift away from the US.

White House spokesman Jay Carney acknowledged disagreements with Saudi Arabia but said: "We work those out in a candid and forthright way as we maintain the basic foundation of a very important relationship."

"We're going to keep working with our Saudi partners because that relationship is very important economically and in national security ways," he told reporters.

Some current and former US officials privately have said the Saudi outburst - all but unprecedented for a kingdom that prefers to conduct diplomacy in the shadows - will have little lasting effect on bilateral ties.

There has been no sign, for example, that the Saudis want to scale back or close US military installations, including a base used to launch unmanned drones against Islamist militants in neighboring Yemen, a US national security source said.

Washington and Riyadh have long been close partners in the fight against Al Qaeda, and there is mutual benefit seen in the long-standing US role as ultimate security guarantor for oil supplies flowing from Saudi Arabia and other Gulf exporters.

"I would not say it's a fundamental breach. There are too many ways we depend" on one another, said a former senior U.S. official who has extensive experience dealing with Saudi Arabia. "It's a family spat (between the U.S. and Saudi Arabia). But it's a serious one."

INTERESTS DIVERGE

Still, some Washington-based analysts say views have become so divergent on issues like Syria, Iran and Egypt that it will be all but impossible for the US and Saudi Arabia to ever return to being as closely aligned as they once were.

Saudi anger boiled over last week when it renounced a coveted seat on the UN Security Council, in protest at what it called international failures to resolve Syria's civil war and grant Palestinians a state.

Behind its concerns was a fear that its closest major ally had failed to respond robustly on Syria - both with threatened military strikes and the arming of anti-government rebels - and would give away too much in any negotiations with Iran.

Simon Henderson, an expert on the Gulf states at the Washington Institute for Near East Policy, said the Saudi message was that it regarded President Barack Obama and his administration as "tone deaf to Saudi interests."

Saudi Arabia, like Israel, is dismayed at the prospect of a US-Iranian thaw because of what it sees as a threat to its own security if Tehran is given freer rein in the region. - Reuters