SAN FRANCISCO (MarketWatch) -- Gold futures climbed to $915 an ounce Tuesday to trade at their strongest levels in a month as a decline in the U.S. dollar and rising oil prices enhanced the metal's appeal as an investment hedge.

Gold for June delivery climbed as high as $915 an ounce on the New York Mercantile Exchange, a level not seen since April 22. It was last up $8.40, or 0.9%, at $914.20.

June gold climbed as high as $915.70 an ounce in electronic trading.

The contract was ready to mark a fourth-straight session of gains. It's already climbed by more than $39, or 4.5%, over the last three trading days.

"The continued gains being made in the energy sector, and the anti-inflationary hedging this is creating," is likely to see gold extend higher, said James Moore, an analyst at TheBullionDesk.com, in a research note.

Crude-oil futures rallied Tuesday, touching a high of $129.45 a barrel in New York, as weakness in the U.S. dollar underpinned oil prices. See Futures Movers.

In the currency markets, the U.S. dollar fell against its major rivals on higher inflation in Germany and tamer U.S. inflation. The dollar index, which tracks the performance of the greenback against other currencies, fell to 72.502 from 73.059 in late North American trading Monday.

Weakness in the U.S. dollar typically benefits dollar-denominated commodities, such as gold and crude oil, because it makes them cheaper for holders of other currencies. See Currencies.

Year to date, gold is up nearly 9% -- unlike most equity markets, said Mark O'Byrne, a director of Gold and Silver Investments Ltd., in a note to clients. And "in the last 12 months, gold is up 37%, and thus corrections are healthy and to be expected."

Also on the Nymex, July silver gained 25 cents at $17.28 an ounce. It's trading at its strongest level since late April. July copper futures fell was down 1 cent to $3.77 a pound.

July platinum fell $3.60 to $2,154.60 an ounce and June palladium shed $5.85 to $445.50 an ounce.

Global platinum supplies weren't enough to meet demand in 2007, platinum group metals refiner Johnson Matthey said Monday in its annual industry review report. But supplies of palladium were more than enough to meet demand. See full story.

Gold ETF demand doubles

Demand for gold exchange-traded funds doubled from the first quarter of last year, but demand for the precious metal in terms of tonnage dropped 16% to its lowest quarterly figure in five years, the World Gold Council said Tuesday. See full story.

"Continuing instability in the equities markets, ongoing fears over the dollar and rising inflation and increased understanding of gold's investment attributes helped spur demand" for ETFs, the Gold Demand Trends report, complied by precious-metals consultancy GFMS Ltd. for the World Gold Council, showed.

Gold ETF demand climbed to 73 metric tons for the first quarter of this year to represent $2.2 billion in dollar terms.