Media playback is unsupported on your device Media caption Bronywn Curtis from HSBC says there is 'brinkmanship' over debt in the US

The price of gold has risen to a fresh all-time high of $1,594.16 an ounce, and the dollar has fallen, on concerns the US may default on its debts.

The moves came after ratings agency Moody's said it may cut the debt rating of the US, warning there was a "rising possibility" it will default.

To avoid default, US politicians have to agree to raise the country's debt limit by 2 August.

Democrats and Republicans are currently in dispute over how best to do this.

'Shockwaves'

The spot price for gold rose to a record high of $1,594.16 an ounce in Thursday trading, before easing to $1,590.66.

Gold is seen as the number one haven purchase in times of economic uncertainty, but analysts said its rise was also caused by the fall in the dollar, which makes the precious metal more affordable for holders of other currencies.

Against the Japanese currency the dollar fell to 78.45 yen at one point, its lowest level since March, before recovering to 79.00 yen.

Investors and bankers assume that governments of the old rich West will eventually take evasive action Read Robert's blog

The dollar also declined against the European single currency, down 0.2% to 0.70430 euros. The greenback also fell slightly against the pound, with sterling rising 0.1% to $1.61240.

European share indexes were slightly lower in Thursday trading, with both Germany's Dax and the UK's FTSE 100 down 0.4%. Japan's Nikkei earlier lost 0.3%.

The market falls were limited because investors assume that US policymakers will eventually do a deal to prevent a default, BBC business editor Robert Peston concluded.

They believe that President Obama and the Republicans will reach an accommodation on spending cuts that would allow the amount that the state can borrow to be increased, he said.

'Shockwaves'

Federal Reserve chairman Ben Bernanke warned that a default by the US on its debt would cause a "major crisis".

Speaking before Congress on Wednesday, he said it "would send shockwaves through the entire financial system".

Media playback is unsupported on your device Media caption Ben Bernanke said a default on the US debt would be ''a major crisis''

As tough negotiations continue on Capitol Hill about raising the debt limit, President Barack Obama reportedly told a top Republican: "Enough is enough."

Talks between Republicans and Democrats are due to resume on Thursday.

"It's a very political environment right now and that's causing all this volatility," said Elke Schoeppl-Jost, chief investment officer at BEA Union Investment in Hong Kong.

Ms Schoeppl-Jost added that markets were concerned about the prospect of further stimulus spending in the US.

On Wednesday, Mr Bernanke said that this remained a possibility if the US economy worsened.

Chinese concerns

China, the largest holder of US debt, reminded Washington of its need to protect investors.

"We hope the US government adopts responsible policy and measures to ensure the interests of investors," said Foreign Ministry spokesman Hong Lei.

China holds about $1.15tn (£713bn) of US debt.

Chinese government economist Yu Bin, who works for China's Development Research Centre, also expressed concern at the prospect of further stimulus spending by the Federal Reserve.

He said such a move could "have a major impact on China's economy" because it would likely increase global commodity prices, most of which are traded in dollars.