GENEVA, Switzerland - Three Americans detained in Iran for almost a year on suspicion of spying are likely to go on trial soon if prosecutors decide enough evidence exists to press charges, Iran's top human-rights official said Friday.

Mohammad Javad Larijani, secretary-general of Iran's High Council for Human Rights, said the latest sanctions imposed by the U.N. Security Council against Iran over its nuclear program should not affect a possible trial.

"I think it should not be very far from now," Larijani said in Geneva, adding that authorities were in the final stages of collecting information and carrying out interrogations.

Sarah Shourd, 31, of California; her fiancee, Shane Bauer, 27, from Minnesota; and their friend Josh Fattal, 28, of Elkins Park, were arrested last July along the Iran-Iraq border. Their families say that the three were hiking in Iraq's mountainous northern Kurdish region and that if they crossed the border, it was accidental.

Iran allowed their mothers to visit in May, the families' first contact with the three since they were taken into custody, but the mothers returned home emptyhanded.

"Our security people are very anxious to see what was behind the intrusion of our borders," Larijani said. He said possibilities ranged from that "they were just hiking and by mistake they came to that area" or "that they were totally spies."

Larijani said his government-approved human-rights body was pressing for a fair handling of the case and for the three to be presumed innocent unless proved otherwise. But he rejected suggestions that the Americans might be swapped for Iranians held in the United States.

"Our judicial system does not agree with these kinds of arrangements," he said.

He said six or seven Iranians were being held by the United States without access to lawyers, diplomats, or their families, among them nuclear scientist Shahram Amiri, who he alleged was kidnapped by the United States while in Saudi Arabia.

U.S. media have reported that Amiri defected to the United States and is assisting the CIA in efforts to undermine Iran's nuclear program.