Gold futures closed higher Wednesday, finishing a few dollars short of the psychological barrier of $600 an ounce, as the dollar fell and Iran signaled it's in no hurry to respond to a western effort to dissuade it from enriching uranium.

Gold for August delivery ended up $10.50 at $591.0 an ounce on the New York Mercantile Exchange, having earlier traded as low as $573.50.

"A confluence of factors is hitting the market at once," said Charles Nedoss, a metals analyst at the Peak Trading Group. The latest news from Iran "makes people a little bit nervous," Nedoss said. "A lot of this also has to do with North Korea and the dollar."

Iranian President Mahmoud Ahmadinejad said that his country would reply by mid-August to the incentive package offered by the permanent members of the United Nations Security Council and Germany to encourage Tehran to halt uranium enrichment, the BBC reported Wednesday. The offer is said to include trade and financial incentives as well as technical assistance in building a light-water nuclear reactor for civilian energy generation.

The announcement might escalate tensions between Iran and the West, since the U.S. has said it expected a response to the June 6 offer "within weeks," according to the BBC. Iran's nuclear program was on the agenda at Wednesday's summit in Vienna between European Union leaders and the Bush administration. The U.N. is concerned that Iran is building a nuclear weapons program although Iran has denied any such plan.

North Korea, which also has nuclear ambitions, reappeared in the news after weekend reports that it's preparing to test launch a missile.

"There's an ongoing trend of these rascal countries taunting the U.S.," said Jon Nadler, investment products analyst at bullion dealer Kitco.com, referring to Iran and North Korea. "It'll continue to keep the tensions on a higher level."

In addition to the uncertainty surrounding Iran and North Korea, the gold market was boosted by the weak dollar, which today fell to a one-week low against the euro after the director of the European Central Bank indicated that interest rates in the euro zone might soon increase again.

James Moore of TheBullionDesk.com said next week's FOMC [Federal Open Market Committee] meeting could also prove pivotal for gold.

The FOMC is expected to increase U.S. interest rates again next week. Both Nedoss and Nadler said that the expected rate hike is already priced in the market.

Other metals also closed higher. July silver added 15 cents at $10.42 an ounce. July platinum added $25.40 at $1,193.90 an ounce, September palladium rose $10.50 at $314.50 an ounce and July copper added 1.9 cents to $3.1905 a pound.

On the supply side, gold inventories were unchanged at 8 million troy ounces as of late trade Tuesday, according to Nymex data, while silver supplies fell 383,660 troy ounces to 104.6 million.

Copper supplies fell by 44 short tons to 7,493 short tons.