This July 2009 video image from the families of Shane Bauer, Sarah Shourd and Josh Fattal shows the trio dancing in the Kurdish city of Irbil, Iraq. The families said the three were simply on vacation when they strayed across the border into Iran. (Shon Meckfessel/Associated Press)

Iran said Monday it will try three Americans who have been in jail since crossing the border from Iraq in July, a move certain to aggravate the United States, which has been calling for their release for months.

Foreign Minister Manouchehr Mottaki did not say when proceedings would begin or specify what charges would be laid, other than to say the Americans had "suspicious aims." In November, Tehran had accused the Americans of spying.

The three Americans, Shane Bauer, 27, Sarah Shourd, 31, and Josh Fattal, 27, were reportedly hiking in Iraq's northern Kurdistan region when they crossed an unmarked border in northern Iraq and were arrested on July 31.

The three were all graduates of the University of California at Berkeley. Bauer and Shourd had been living in Damascus, Syria, and doing work as freelance journalists, while Fattal had been overseas as a teaching assistant with the International Honors Program.

U.S. Secretary of State Hillary Rodham Clinton said from Washington that Iran's move was "totally unfounded," and again appealed for their release.

"We consider this a totally unfounded charge," she told reporters. "There is no basis for it. The three young people who were detained by the Iranians have absolutely no connection with any kind of action against the Iranian state or government."

"We appeal to the Iranian leadership to release these three young people and free them as soon as possible," she said.

Trio could be bargaining chip in talks

Mottaki told reporters on Monday that the three were still being interrogated.

"They will be tried by Iran's judiciary system and verdicts will be issued," he said at a press briefing.

Swiss diplomats have met with the trio twice at Iran's Evin prison and said they are healthy. The Swiss Embassy maintains an American interests section because the U.S. and Iran do not have direct diplomatic relations.

The U.S. government is concerned Iran is using the case as a bargaining chip in negotiations for anything from Iranians detained in America to multilateral discussions over Iran's nuclear enrichment program.

President Mahmoud Ahmadinejad brought up the case of the three Americans last month, drawing a link between their situation and that of Amir Hossein Ardebili, an Iranian facing up to 140 years in prison after pleading guilty to plotting to ship sensitive U.S. military technology to Iran.

Arrests made in student protests

Iran also announced on Monday it had arrested several people accused of destroying photos of the Islamic Republic's revered founder and current spiritual leader during demonstrations last week, according to the official IRNA news agency.

Last week student protesters burned and trampled on pictures of Supreme Leader Ayatollah Ali Khamenei in protest of June's presidential election, which they say was rigged in favour of Ahmadinejad.

But they denied government claims they also tore up a photo of the leader of Iran's 1979 revolution, the late Ayatollah Ruhollah Khomeini. They accused the government of staging the video of someone destroying Khomeini's picture to justify a continued crackdown of dissenting voices.

Human rights groups and Iran's opposition have criticized Iran's trials of political demonstrators in the aftermath of the presidential election as shams and said televised confessions from defendants were scripted by authorities and extracted through pressure.

With files from The Associated Press