Gulf crude exporters, which mostly peg their currencies to the dollar, are major holders of Treasuries and other US assets, with oil — priced in dollars — their main source of government income.

Asked if the OPEC member was worried about the US debt and was considering purchasing euro zone sovereign debt, Al-Jasser said: "No", Reuters reported.

Jarmo T. Kotilaine, chief economist at the National Commercial Bank, said: “Al-Jasser's remark makes every sense, both from a structural perspective and in view of the prevailing economic realities and risks. The Kingdom's heavy reliance on dollar-denominated oil revenues and a long and successful history of maintaining a credible peg to the US dollar create a different backdrop for policy than is the case for instance in China. With a steady influx of US dollars, the Kingdom will naturally seek to place a significant portion in highly rated US dollar-denominated securities.”

Even following Standard & Poor’s downgrade, he said there are few, indeed effectively no, credible contenders to US Treasuries in this regard.

Moreover, recent indications suggest that further downgrades are unlikely in the near term while efforts toward fiscal consolidation are under way, albeit in a politically charged atmosphere. The dollar peg itself is not in question. If anything, its role as an anchor of stability and predictability has been enhanced in an environment of intense global economic uncertainty.

“Significant diversification into European bonds would also represent a risky choice at a time when fiscal pressures in a number of euro zone countries are intense and a credible, sustainable solution to the crisis is yet to be formulated. Even in an optimistic scenario, the European bond markets are likely to experience significant volatility and hence do not represent an obviously more attractive alternative to US Treasuries,” Kotilaine said.

Paul Gamble, head of research at Riyadh-based Jadwa Investment, said: “It is understandable that the Kingdom will say it is not concerned about the US rating downgrade as Saudi Arabia is a large holder of US government debt. The US is still top-rated by the two other leading credit rating agencies and no other country provides the same size, breadth of liquidity of capital market instruments as the US does. Given problems in the euro zone, a cautious stance toward sovereign debt from the region is appropriate.”

Ratings agency S&P last month cut the US long-term credit rating by one notch in an unprecedented blow due to concerns about the nation's budget deficits and climbing debt burden.

Fears of debt contagion in the euro zone have been shaking the global markets over the past months. On Wednesday, the euro and European stocks were lifted by an announcement by the head of the European Commission that it would soon present options for issuing a common euro zone bond.

Al-Jasser also told reporters after meeting central bank governors of Qatar, Kuwait and Bahrain in Doha that the economic situation in the four countries aiming to form a monetary union was "excellent" and that a plan to launch a Gulf single currency was on track.

"There is no postponement, and I have said from the beginning that there will not be a specific date (for the single currency launch) ... the economic situation in our countries is excellent and nothing is delaying the currency," Al-Jasser was quoted by Reuters as saying.