A KFC-branded fried chicken restaurant that opened its doors Sunday night in Iran's capital city of Tehran was shut down after just one day in operation.

The restaurant, KFC Halal, which Iranian news agency Tasnim called "the first American branch" of its kind, had set up shop in West Tehran after seemingly obtaining approval from the country's Ministry of Industry, Trade and Mines, and showed happy customers lining up for chicken on its website and Instagram page.

Customers are seen lined up in Tehran's KFC in a photo posted on its website. Image: kfchalal.ir

ازدحام جمعیت در افتتاح اولین شعبه کی اف سی حلال در ایران ... خوش آمدید مردم ایران A photo posted by kfciran (@kfciranian) on Nov 1, 2015 at 6:30am PST

But by Tuesday, Iranian police had shut it down. A sign posted on its door read it was "closed until further notice." The reason given: Its decor too closely resembles the U.S. flag, and its presence "can be seen as a part of American influence into Iranian culture," the agency says. "The U.S. is one of Iran's major enemies and this will have grave dangers for the country."

First branch of #US fast food restaurant @KFC was shut down in #Iran's #Tehran soon after its opening pic.twitter.com/S2QGtypHqI — Tasnim News Agency (@Tasnimnews_EN) November 3, 2015

"The shutting down of Halal KFC was due to a misunderstanding," the store's manager, Abbas Pazuki, reportedly said. "We are part of a brand known as Halal KFC, which comes from Turkey. It belongs to Muslims and its target market is Muslim nations," he clarified. That KFC, he says, is a "rival of the American KFC."

"We are shocked with the news that an illegitimate KFC outlet has opened in Tehran, Iran," Laurie Schalow, a KFC spokesperson, told Mashable. "No franchise rights have been granted to any party in Iran. We are in contact with local authorities and external advisers and will be filing a legal action against any company or individuals claiming to have rights to open KFC."

An image on the Iranian KFC's website illustrates the partnership between a Turkish KFC and the one that opened in Tehran. Image: http://kfchalal.ir/

Ali Fazli, who is identified as Head of the Trade Chamber of Iran by the Iranian News Labor Agency, also said the KFC restaurant had "nothing to do" with its American namesake. "No Western fast food has any branches in Iran," he said.

Despite a thaw in relations during the nuclear talks, Iran's hardliners are wary of embracing any Western-style restaurants, which they say is "behavior contrary to Islamic-Iranian culture and traditions." Iran's Supreme Leader, Ayatollah Khomeini, has called the establishment of such restaurants a red line that would not be crossed.