Iran on Wednesday summoned the Swiss diplomat representing American interests here to protest the U.S. forces' detention in Baghdad of eight Iranians, including two diplomats, the Foreign Ministry said.
The Iranian delegation was later released by U.S. forces just hours after being detained because unauthorized weapons were found in their cars, according to the U.S. military.
Foreign Ministry spokesman Mohammad Ali Hosseini called the U.S. action an act of "interference" in Iraq's internal affairs and "inconsistent" with the responsibilities of U.S.-led occupation forces in Iraq.
The charge d'affaires at the Swiss Embassy was summoned to Iran's Foreign Ministry over the "illegal" detention of members of an Iranian Energy Ministry delegation, state-run television reported.
Switzerland looks after the U.S. interests in Tehran in the absence of formal diplomatic relations between Tehran and Washington.
Troops seized an AK-47 assault rifle and two 9mm pistols that had been in the possession of the Iraqis in the group. The Iraqis were serving as a protective detail but had no weapons permits, the U.S. military said.
At the hotel later, U.S. troops confiscated a laptop, cell phones and a briefcase full of Iranian and U.S. currency in the hotel, the military said.
Video shot Tuesday night by AP Television News showed U.S. troops leading blindfolded and handcuffed men out of the hotel in central Baghdad.
Hosseini said delegation was in Baghdad to hold talks with Iraqi officials on building a power plant when they were detained by U.S. forces in the hotel they were staying.
"These actions are contrary to the responsibilities of foreign forces in Iraq and is another mistake in the erroneous behavior of the Americans," Hosseini was quoted by the broadcast as saying.
The incident came as tensions between Washington and Tehran were already strained by the detention of each other's citizens as well as U.S. accusations of Iranian involvement in Iraq's violence and alleged Iranian efforts to develop nuclear bombs.
On Tuesday, President Bush accused Iran's leadership of trying to destabilize Iraq, saying, "I have authorized our military commanders in Iraq to confront Tehran's murderous activities."
President Mahmoud Ahmadinejad, for his part, said that U.S. political influence in Iraq is "collapsing rapidly" and that Tehran is ready to help fill any power vacuum.