Iran's foreign ministry on Thursday summoned the Iraqi and Swiss envoys to Tehran over the detention of five Iranian staffers at a diplomatic mission in northern Iraq, state-run television reported.

The broadcast said the ministry had summoned the ambassadors and "demanded an explanation" about the incident. Switzerland represents American interests in Iran, where there is no U.S. embassy.

The summons followed a raid in Iraq, where multinational forces stormed the building of an Iranian consulate in the Kurdish-controlled northern city of Irbil, 350 kilometres from Baghdad at about 3 a.m.

They detained the five staffers and confiscated computers and documents, two senior local Kurdish officials said, speaking on condition of anonymity
because of the sensitivity of the information.

The U.S. military issued a statement saying it had taken six people into custody in the region but did not mention a raid on the Iranian consulate. It declined further comment.

Iran's foreign ministry spokesman Mohammad Ali Hosseini told state-run radio that the raid was "against a diplomatic mission" since the "presence of Iranian staffers in Irbil was legal."

Hosseini claimed the action by the U.S.-led coalition reflected "continuation of pressure" on Iran, aiming to "create tension" between Iraq and its neighbours.

A resident living near the mission said troops used stun bombs in the raid and brought down an Iranian flag that was on the roof of the two-storey yellow house. As the operation went on, two helicopters flew overhead, said the resident on condition of anonymity because he feared retribution.

"They took five Iranians with them and at about seven in the morning they handed over the house to Kurdish peshmergas," he said.

In the early afternoon, a number of Kurdish guerrillas could be seen around the building preventing people from getting close to the house and not allowing cameramen and photographers to take pictures.

The report, which first appeared on Iraq state television, also was confirmed by a Shia official in the capital, who declined to be named because of the sensitivity of the information.

The motive for the raid was not known, but it came as tensions are high between Iran and the United States. The Bush administration has accused Iran of trying to develop nuclear weapons and of helping fuel violence in Iraq. Iranian President Mahmoud Ahmadinejad, meanwhile, is trying to expand Iran's role in Iraq as a counter to U.S. influence in the Gulf region.

Late last month, U.S. troops elsewhere in Iraq detained at least two Iranians and released two others who had diplomatic immunity.