The standoff over the three American hikers detained in Iran since July intensified yesterday after Iran's foreign minister told Iranian state TV that the three - including Joshua Fattal, raised in Elkins Park - entered Iran "with suspicious aims," are under intense "interrogation," and cannot escape facing trial.

Foreign Minister Manouchehr Mottaki did not elaborate, although a Tehran prosecutor had earlier accused the three of spying.

Secretary of State Hillary Rodham Clinton branded the allegations "totally unfounded."

Mottaki said the three friends, who met as students at the University of California at Berkeley, would be tried. He did not identify the charges or give a date for the trial. A message seeking clarification was not immediately returned by Iran's Mission to the United Nations.

Freelance photographer Shane Bauer, 27, of Minnesota, language teacher Sarah Shourd, 31, of California, and environmentalist Fattal, 27, were arrested July 31 while trekking in Kurdish-controlled northern Iraq.

Their families and supporters say they strayed into Iran across a remote, unmarked section of the border.

Clinton, speaking to reporters in Washington, said Iran should "release these three young people . . . as soon as possible" and called the spying charge "totally unfounded."

"There is no basis for it," she said. "They were out hiking and unfortunately, apparently, allegedly walked across an unmarked boundary."

Leigh Goldenberg, along with Fattal and other classmates, graduated from Cheltenham High School in 2000. She and several graduates from the Class of 2000 have helped organize vigils to keep a spotlight on the case.

"Josh was our student council president and very well-known. If something like this happened to almost anyone we graduated with, people would have rallied around," said Goldenberg, who works in the marketing department of the Arden Theatre Company in Old City. "But he was definitely a force in high school and people are remembering that now."

The next vigil will be next Tuesday in Cheltenham, she said, with details to be on www.freethehikers.org, a Web site created by supporters.

"When news of their arrests first came out I thought it would be over quickly," Goldenberg said. But the summer and fall rallies have given way to vigils that require winter coats now, she said, and it's clear it will take longer.

"There is always hope," she said. "And after every vigil we just keep hoping they are going to be home and we won't have to plan another one."

In another sign of the lasting impression Fattal left at the school, his senior-year English teacher, Rick Topper, wrote recently in a testimonial that Fattal was "engaged with the world, alive to its possibilities, and responsive to the plight of those who weren't given his gifts. I'm not surprised that he worked in a nonprofit as a young adult, nor am I surprised that he would take time to explore other cultures."

Fattal's family in Elkins Park declined to comment on Mottaki's announcement.

Efforts to free the hikers are hampered by the fact that the United States severed diplomatic relations with Iran in 1979 after militants seized the U.S. Embassy in Tehran and held its staff hostage for more than a year.

Since then U.S. interests in Iran have been represented by Swiss government envoys.

U.S. efforts to limit Iran's nuclear program add another layer of complication, as do tensions over the fate of several Iranians under arrest in the United States, including Amir Hossein Ardebili, 35, whom federal prosecutors accused of trying to procure U.S. military equipment for Iran.

Last month, Iran's President Mahmoud Ahmadinejad raised the possibility that Tehran was seeking to use the hikers as bargaining chips in a potential exchange for the imprisoned Iranians when he drew a link between the case of the hikers and Ardebili, who was targeted in 2004 in a sting run by undercover federal agents in Philadelphia.

Ardebili pleaded guilty in May 2008 and was sentenced yesterday in a Wilmington court to a five-year term.

Even if the hikers are tried and convicted, there is precedent for freeing them soon after. Iranian American journalist Roxana Saberi was convicted of espionage and sentenced to eight years in prison in January but was freed on appeal in May. Canadian Iranian journalist Maziar Bahari was arrested in a postelection crackdown on dissidents in June but left Iran in October.

Contact staff writer Michael Matza at 215-854-2541 or mmatza@phillynews.com.

This article includes information from the Associated Press.