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Porsche has become the latest international automaker to pull its business out of Iran in an apparent response to an effort by two U.S.-based advocacy groups to step up pressure on the Tehran regime, FoxNews.com has learned.

United Against a Nuclear Iran and Iran Watch List launched their campaign in 2010 after they discovered the Iranian auto industry, the 13th-largest in the world, is dominated by members of the Iranian regime and the Islamic Revolutionary Guard Corps.

"We have to send a message to that regime that no longer can it be business as usual until they renounce their nuclear weapons program and stop sponsoring terrorism around the world," said former U.S. Ambassador to the United Nations Mark Wallace, who heads United Against a Nuclear Iran.

Wallace says the auto sector feeds the Iranian regime not only as “a massive source of revenue,” but also as a means of accessing advanced foreign technologies and products.

In spite of economic sanctions, Iran’s auto industry has grown to be the largest in the Middle East, building more than 1.6 million vehicles last year, according to United Against a Nuclear Iran. Iran’s two largest automakers, the Iran Khodro Group and the Saipa Group, are subsidiaries of the Iranian Development and Renovation Organization, the same government body involved in developing the regime’s nuclear and missile programs. Iran’s third largest automaker, the Bahman Group, is nearly half-owned by the Revolutionary Guard.

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    Iran’s auto industry, which has business relationships with Nissan, Fiat, Volvo and Peugeot, employs thousands of workers and exports vehicles to more than 30 countries. Porsche, which just last Friday joined Hyundai in agreeing to pull out of Iran, reportedly sold $17 million worth of cars through its dealership in Tehran in just the past few months. A spokesperson for the German automaker confirmed to FoxNews.com the company's intention to leave the country.

    "You can't have it both ways. If you want to do business in Iran, forget about doing business in the United States, forget about the American consumer, because the American consumer is not going to stand for companies propping up the Iranian regime," said New York City Public Advocate Bill de Blasio, who heads up Iran Watch List.

    “The leadership in Iran is painfully aware of the fact that companies are leaving,” de Blasio said, pointing out that only the elites in the Iranian government and oil industry can afford luxury cars such as Porsches.

    Wallace singled out Nissan and Peugeot as companies putting up resistance to leaving Iran entirely.

    "Nissan appears to be the vehicle of choice of Iranian President Mahmoud Ahmadinejad, who often rides in an armored Nissan SUV," he said.

    When asked about their business in Iran, Nissan’s vice president of corporate communications wrote to Fox News: "Nissan does not sell cars in Iran. Local manufacturer Pars Khodro is permitted, by license, to sell certain Nissan model names in the country. This is a limited-scale business relationship which follows all U.S. and other foreign export control regulations."

    In a letter to Nissan, de Blasio wrote that as the winner of New York City’s “Taxi of tomorrow” completion, a contract worth roughly $1 billion to supply the city with taxis for the next several years, it is not acceptable to “taxpayers and taxi riders for the maker of our future taxis to continue to conduct business in Iran and support a dangerous regime in Tehran.”