As many as three U.S. missiles aimed at targets in Iraq may have landed in Iran, two officials at the Pentagon said Saturday.

The State Department assured Iran, in a message sent through Swiss intermediaries, that the United States was investigating. Spokesman Philip Reeker offered public assurances that the United States respects Iran's sovereignty and territorial integrity.

The official Iranian news agency reported that four rockets have landed in Iran over the past two days.

U.S. and Iranian officials are discussing the matter and Iran realizes that any strike was unintentional, said the officials, speaking on condition of anonymity.

At least three people were injured, according to the Islamic Republic News Agency.

Iran also complained that coalition aircraft have violated its airspace near the southern Iraqi port of Basra. Iran has closed its airspace to coalition and Iraqi warplanes.

In a letter to U.N. Secretary-General Kofi Annan, Iranian Foreign Minister Kamal Kharrazi urged the world body to act to stop the invasion of Iraq, the Islamic Republic News Agency reported.

Kharrazi said the war was a strike against an Islamic country, a violation of international law and that it paved the way for "the emergence of a chaotic world in which force dictates the rules and anarchism is the name of the game."

British Defense Secretary Geoff Hoon said he could not confirm reports of stray missiles landing in Iran. "I have seen these suggestions and obviously they are being investigated and we are continuing our contact with the government there," he said.

In Tehran, an Iranian lawmaker said a missile hit a government building in western Iran near the Iraqi border on Friday, injuring two people.

The Foreign Ministry summoned the ambassadors of Britain and Switzerland — which represents U.S. interests in Iran — to protest, the Iranian news agency said, without giving details on the violations.

The missile struck an Oil Ministry building in Abadan, said Mohammad Kianoush Rad, a legislator for the southwest Iranian province of Khuzestan, where the city is located. Two people were injured, he said.

"This is unacceptable," he told The Associated Press. "We hope this was only a stray missile."

He said it was not clear where the missile had come from. Abadan is about 30 miles east of Basra, which was under attack by U.S.-led forces.

The news agency also reported that two rockets hit the village of Manyuhi near the border with Faw on Saturday.

An Iranian government spokesman, Abdollah Ramezanzadeh, confirmed that a missile had landed somewhere in Iranian territory near the Iraqi border, but he would not give details.

He said that Iran had demanded explanations from the Swiss and British embassies in Tehran. The United States has not had diplomatic relations with Iran since the 1979 Islamic revolution.