US tourists held by Iran were warned by the police

(AFP)

TEHRAN — Iran has arrested three Americans who "infiltrated" from Iraq, state television said on Saturday, as Washington sought confirmation those picked up are backpackers who reportedly strayed across the border.

"An informed Iranian source confirmed the arrest of three Americans after they infiltrated through the Iraqi border," the Arabic-language Al-Alam station reported. Another state channel said they were military personnel.

The United States, which does not have diplomatic ties with the Islamic republic, said it has asked Switzerland, which represents its interests in Tehran, to confirm the Iranian reports.

"We have asked our Swiss protecting power to confirm these reports with Iranian authorities and, if true, to seek consular access," US State Department spokesman Robert Wood said in a statement in Washington.

"The protection of American citizens is our highest priority."

The autonomous Kurdish government in northern Iraq, from where the three Americans had set off, said it was in contact with Iranian and US officials in a bid to resolve the issue.

A Kurdish official identified the three as US backpackers and said they were arrested after having been warned on the Iraqi side not to hike in the mountains because of the proximity of the border with Iran which is not clearly marked.

Beshro Ahmed, media adviser for general security in Iraq's autonomous Kurdish region, said the two men and a woman had entered from Turkey earlier along with a fourth American who did not join the trek because he was ill.

According to CNN, Iran detained the three US nationals on Friday after they crossed into the country from Iraqi Kurdistan.

Ahmed named the three as Shane Bower, Sara Short and Joshua Steel while Shaun Gabriel Maxwell stayed behind in a hotel in the Kurdish region's second largest city of Sulaimaniyah.

"On Thursday, three of them went to the summer resort at Ahmed Awa," Ahmed said of an area about 90 kilometres (55 miles) northeast of Sulaimaniyah.

The three Americans stayed in a youth hostel in the mountainous region and "the (Kurdish) tourist police in the area asked them not to climb the mountains because the Iranian border was very close," Ahmed said.

"On Friday, they went close to the mountains, and climbed them. Then they called their friend in the hotel telling him that they were arrested by Iranian forces at the border," Ahmed said.

"Shaun was in the hotel and he called the US embassy in Iraq to tell them about this information, and the Americans came to the hotel and took him."

The Kurdish regional government said in a statement late Saturday that it was maintaining close contact with the Iranian consulate in Arbil as well as with US officials "in order to solve the problem."

Iranian state television, without quoting a source, said on an earlier Saturday news bulletin that three US military personnel had gone missing near the border.

"Three US military personnel went missing in an area bordering Iran-Iraq," the announcer said.

"The reason for the presence of these American soldiers is not known. The Western media, in the past few days, extensively propagated that these three US personnel have been kidnapped."

But an official at the Pentagon in Washington has insisted that no US military personnel were involved.

US-Iran tensions have been high for years, with the Islamic republic deriding the United States as the "Great Satan" and President Barack Obama's predecessor, George W. Bush, labelling Tehran part of an "axis of evil."

The acrimony has increased as Washington, despite Obama offering Tehran a chance to turn the page, has expressed mounting concern over Iranian nuclear ambitions and its disputed June presidential election.