(CNN) -- Iran summoned the Swiss diplomat who represents U.S. affairs to its Foreign Ministry on Wednesday to protest the detentions of eight Iranian delegates in Baghdad, according to Iranian state-run media.
Footage from Associated Press Television shows blindfolded men being escorted from a Baghdad hotel.
The Iranians who were arrested Tuesday worked for Iran's Energy Ministry and were in Baghdad at the invitation of Iraqi officials to sign an energy supply contract, said Yassin Majid, an aide to Iraqi Prime Minister Nuri al-Maliki. The delegates were released Wednesday, he said.
Video footage of the Tuesday arrests showed U.S. soldiers escorting 10 people -- blindfolded and some with their hands bound in front of them -- from a Baghdad hotel into military vehicles.
A senior U.S. official familiar with the incident told CNN the delegates should not have been detained in such a fashion. It was a mistake ordered by a low-level commander, the official said. Watch the men being escorted from the hotel »
The U.S. military has said the delegates' Iraqi security escorts were carrying pistols and a rifle but had no weapons permits.
Iranian Foreign Ministry spokesman Mohammad Ali Hosseini called the detentions an "interventionist act," according to the Islamic Republic News Agency. He further said that Iraqi officials and the Iranian Embassy secured their release so they can continue their work -- discussing the construction of a power plant in Iraq, IRNA reported.
The Swiss diplomat was called and "Iran presented its strong protest to U.S. behavior which is contradictory to the international laws and regulations and asked for explanations," Hosseini said, according to IRNA..
Because the United States has no diplomatic relations with Tehran, the Swiss charge d'affaires represents U.S. interests in the Islamic republic.
In Washington, State Department spokesman Tom Casey said Wednesday that the incident is not expected to affect U.S. relations with Iran or Iraq.
"This was something that happened in the routine course of military operations in Baghdad," Casey said. "The issue was handled and looked at. The individuals have subsequently been released. And I think that's pretty much case closed."
The United States repeatedly has expressed reservations about the Iranian role in neighboring Iraq. Washington has accused Tehran of supplying weapons to insurgents and training Shiite militants, allegations that Iran denies.
On Tuesday, President Bush said he has "authorized our military commanders in Iraq to confront Tehran's murderous activities."
"The Iranian regime must halt these actions," he said. "And until it does, I will take actions necessary to protect our troops."
Despite U.S. aversion to Iranian involvement in Iraq, Baghdad's Shiite-dominated government has reached out to Tehran, and al-Maliki recently returned from a visit to the Iranian capital. Iranian President Mahmoud Ahmadinejad recently accepted an invitation to visit Baghdad, but no date has been set.
The Iranian delegation and its security detail were detained after U.S.-led coalition forces searched their four vehicles at a checkpoint near a Sheraton hotel in eastern Baghdad's Rusafa district, according to the U.S. military.
The seven Iraqi escorts, all of whom carried Iraqi Energy Department badges, had an AK-47 and 9 mm pistols, but not weapons permits, the military said. The Iraqis also were carrying Iranian currency, according to the U.S. military.
After stopping the delegates at the checkpoint, coalition forces allowed them to proceed to their hotel, where their rooms were searched.
There, soldiers confiscated cell phones, a computer and a briefcase filled with Iranian and U.S. money. The officials and their security detail then were arrested and "taken to a coalition facility for questioning," the U.S. military said.
The United States is still holding five Iranians detained during a raid in January in the northern Iraqi city of Irbil. The Iranians are accused of supporting Shiite militias in Iraq.
Iran has protested their detention, saying they are diplomats and accusing the United States of breaking international law by raiding a consulate Iranestablished in Irbil. The United States says the men were taken at a liaison office that lacks diplomatic status.
Meanwhile, U.S. officials have expressed displeasure over Iran's detention of several Iranian-Americans accused by Iran of working against the Islamic republic.
One of those detained, Haleh Esfandiari, an employee of the Washington-based Woodrow Wilson Center for International Scholars, was released from Tehran's notorious Evin prison last week but is waiting to leave the country. E-mail to a friend
CNN's Barbara Starr contributed to this report.