Iran's security officials confirm the arrest of three American nationals in Western city of Marivan, charging the detainees with "illegal entry", Trend News reported with reference to Press TV.  

"The three, who have not been identified yet, were arrested on the Malakh- Khur border area in Marivan," Iraj Hassanzadeh, the deputy governor of Kurdistan for political-security affairs, told Fars news agency.

He said the 'middle-aged' men were traveling on Syrian and Iraqi visas, noting all those who try to 'illegally' cross Iran's borders will be arrested.

The US had earlier asked Swiss embassy in Tehran -- which looks after US interests in Iran as the two countries have no diplomatic ties -- to follow the case of the three Americans.

A Kurdish official in northern Iraq told AFP that the US nationals were backpackers who were arrested after warnings on the Iraqi side not to hike in the mountains because of the proximity of the border with Iran.

However, Colonel Anwar Haj Omar of the Halabja police force in northern Iraq linked the three Americans to the Central Intelligence Agency (CIA), according to Voices of Iraq.

Head of the Iranian Parliament's foreign policy committee, Alaeddin Boroujerdi, has said the case will take its natural course.