Gulf states, which mostly peg their currencies to the US dollar, are major holders of Treasuries and other US assets, with oil — priced in dollars — their major source of revenue.

Asked whether the UAE was considering changing its policy on buying US government bonds after a bill to increase the United States' debt issuance limit was defeated in Congress on Tuesday, Sultan Nasser Al-Suweidi said: "No, there is no change."

"For the time being, I do not think there is a strong move in GCC (Gulf Cooperation Council) countries following Asian central bank investment policies," Al-Suweidi told reporters on the sidelines of a financial workshop in the UAE capital.

The UAE central bank re-started purchases of foreign securities in May 2010, after reducing its holdings to almost zero following the 2008 global financial crisis.

It held 80 billion dirhams ($22 billion) worth of foreign paper in March, almost 44 percent of its total reserves, down slightly from 82.1 billion dirhams in February, data shows.

"It is a treasury department policy. There are guidelines that are reviewed from time to time. If there is a need to move into Treasuries in a bigger way that would be discussed and decided," Al-Suweidi said.

US lawmakers defeated on Tuesday a bill to raise the $14.3 trillion debt limit without conditions. So far, markets are little concerned by the possibility of default on what is viewed as one of the world's safest investments.

Asian central banks have stepped up purchases of dollar-based foreign reserves to combat currency appreciation and keep exports competitive.

"In the case of the UAE, you have a US dollar peg and a large share of US dollar trade. These factors mean that I would expect the currency reserves to remain predominantly US dollar-based for the foreseeable future," said Giyas Gokkent, chief economist at the National Bank of Abu Dhabi.

The UAE central bank said last year it holds nearly all of its foreign exchange reserves in US dollars with only small amounts of other currencies such as the Japanese yen.

Central banks in the Gulf, the world's top oil-exporting region, usually do not disclose a detailed composition of their foreign currency reserves.

Asked if the UAE, the world's No.3 oil exporter and home to one of the largest sovereign wealth funds, might consider diversifying reserves into the Chinese yuan, Al-Suweidi said it depended on China relaxing its currency controls.

"It depends on the Chinese themselves because they are not yet prepared to allow the yuan to be a reserve currency," he said. "If China relaxed controls then that will go to the investment committee within the treasury department of the central bank and then they will make a decision."

The market mostly assumes that convertibility of China's yuan is some years off, but the currency has gradually grown more accessible and there have been signs of Asian central banks showing an interest in buying yuan-denominated bonds.

Trade between China and the six Gulf Arab countries — the UAE, Saudi Arabia, Kuwait, Qatar, Oman and Bahrain — stands at around $100 billion, the UAE foreign minister said in May.

"At some point there should be some diversification but I would not expect that it to be such that they hold significantly larger amounts of other currencies," Gokkent said.

"US dollar assets are very, very liquid. You do not have many other assets that you can get in and get out," he said.

Al-Suweidi earlier told the workshop that the OPEC member needs to increase efforts to create a local debt market. The UAE is in the final stages of approving a law that will allow it to issue its first ever federal sovereign bonds.