Gold rose above $1,500 an ounce on Wednesday for the first time ever as the dollar wilted, oil rose, worries over the U.S. economic outlook boosted demand for the metal as a haven and rising inflation lifted Asian demand.

The Reuters-Jeffries CRB index was on track for its biggest one-day gain in a fortnight as commodity prices rallied.

Spot gold hit a high of $1,505.40 an ounce and was bid at $1,501.10 an ounce at 1403 GMT, against $1,493.90 late in New York on Tuesday. U.S. gold futures for June delivery rose $6.70 an ounce to $1,501.80.

Silver tracked gold higher, extending a stellar performance that has seen the grey metal outperform other precious metals this year. Silver hit a 31-year high at $44.79 an ounce and was later bid at $44.72 against $43.89.

Gold prices are up 5 percent in April and look set to extend gains as the metal's appeal as a haven from risk was boosted by talk that Greece may have to restructure its debt and Standard & Poor's threat to downgrade America's triple-A credit rating.

Gold has been acting as a currency in its own right, and that is why we are up at $1,500, said Simon Weeks, head of precious metals at the Bank of Nova Scotia. There is an awful lot of bad news in the price. The S&P comment the other day has given us the final kicker to get up here.

While investors in the United States and Europe are seeing the metal chiefly as a safe store of value and a hedge against currency devaluation, stronger inflation and rising consumer incomes in China and India are also boosting demand there.

The theme of longer term higher inflation than we have seen in the last 10 years in China is a pretty solid view, so gold is going to be an asset class that is probably going to be more in favor in China than it has been in the past, said Macquarie analyst Hayden Atkins.

China is the world's second-biggest gold consumer behind India, as well as being the biggest producer.

RISING OIL, WEAKER DOLLAR

In the short term, losses in the dollar on Wednesday are supporting the precious metal above $1,500 an ounce. The dollar is usually sold off when risk appetite firms, as reflected in a rise in stock markets on Wednesday.

The dollar slid to its lowest in 15 months against the euro as the single currency was boosted by higher risk appetite and after a bond auction from Spain was well received by investors.

Weakness in the dollar boosts gold's appeal as an alternative asset and makes dollar-priced commodities cheaper for holders of other currencies. Gold priced in euros and sterling remained off recent highs on Wednesday.

Oil prices also recovered, rising back toward the multi-year highs they hit earlier this year as unrest in the Middle East and North Africa sparked fears of a supply outage.

Higher oil prices tend to benefit gold, both because they can boost commodities as an asset class and lift interest in gold as a hedge against oil-led inflation.

The gold:silver ratio -- the number of silver ounces needed to buy an ounce of gold -- meanwhile fell to its lowest since 1983 below 34.

The last time silver was this expensive in relation to gold was almost 28 years ago, said Commerzbank in a note. Both precious metals are still reaping the benefit of the news of recent weeks and days.

Platinum was at $1,800.99 an ounce against $1,761.50, while palladium was at $754.97 against $726.95.

(Editing by Alison Birrane/James Jukwey)