TEHRAN, Iran — Iran took a step yesterday toward establishing an oil market denominated in euros, a plan analysts described as highly unlikely to materialize but which in theory could have serious consequences for the U.S. economy.

Iranian state-run television said the country's Oil Ministry granted a license for the euro-denominated market, an idea first floated back in 2004, though just who would trade on it remains unclear.

If the market were to succeed — or if Iran simply demanded payment for its oil in euros — commodities experts said it could lead central bankers around the world to convert some dollar reserves into euros, possibly causing a decline in the dollar's value.

Oil is currently denominated in dollars around the globe, whether through direct sales between producers and consumers or in trades made on markets in New York and London.

But if one day the world's largest oil producers allowed — or worse, demanded — euros for their barrels, "it would be the financial equivalent of a nuclear strike," said A.G. Edwards commodities analyst Bill O'Grady.

"If OPEC decided they didn't want dollars anymore," he added, "it would signal an end of American hegemony by signaling an end to the dollar as the sole reserve currency."

If the dollar lost its status as the world's reserve currency, that would force the United States to fund its massive account deficit by running a trade surplus, which would increase inflationary pressures.

O'Grady said there are practical reasons why the Iranian threat is an empty one.

For starters, Iran is not a very attractive site for a market, given the volatile nature of its politics, the U.S. sanctions against it and the lack of a fair legal system. Moreover, there is no indication that the European Union is interested in vying to become the world's central bank, which requires a willingness to run large currency deficits, he said. For the U.S., that has meant allowing cheap imports to undermine the strength of some major industries, including textiles, autos and electronics manufacturing.

Iranian legislators earlier this year urged the government to set up the market to reduce the United States' influence over the Islamic republic's economy. They also criticized Oil Minister Sayed Kazem Vaziri Hamaneh, saying he had delayed setting up the bourse.

First floated in 2004 when reformist President Mohammad Khatami was in power, the idea of a euros-traded oil bourse gained new life after the stridently nationalist Mahmoud Ahmadinejad was elected president last summer.

Iran is the fourth-largest oil producer in the world, the second-largest in the Organization of Petroleum Exporting countries and controls about 5 percent of the global oil supply, so it has a measure of influence over international oil markets. Tehran also partially controls the Persian Gulf's Strait of Hormuz, through which much of the world's oil supply must pass.

Iran has sought to wield its oil resources as a bargaining tool in Tehran's ongoing standoff with the West over its nuclear program.