The U.S. State Department says it is asking Swiss diplomats in Iran to investigate Iranian media reports that three American tourists were arrested after entering the country without permission.
Iran's state-owned television, al-Alam, reported the arrests Saturday, saying the tourists illegally entered the country through Iraq's northern border.
Authorities in Iraq's autonomous Kurdish region say the two men and a woman were on a hiking trip near the border when they apparently crossed into Iran on Friday.
Kurdish security officials say the hikers contacted another member of their travel group to say they were confronted by soldiers after entering Iranian territory.
The Americans arrived in the Iraqi Kurdish capital of Irbil earlier in the week, and were staying at Ahmed Awa a mountain resort near the border with Iran. Kurdish officials say they had been warned that the Iranian border was very close.
Some information for this report was provided by AFP and AP.