Iran said Monday it would try three Americans jailed since crossing the border from Iraq in July, a step certain to aggravate the US at a time when Tehran is locked in a standoff with the West over its nuclear program. Foreign Minister Manouchehr Mottaki did not say when proceedings would begin or specify the charge other than to say the Americans had “suspicious aims.” In November, however, authorities accused the Americans of spying. There are concerns in the US that Iran could use them as bargaining chips in talks over its nuclear program or in seeking the return of Iranians they say are missing. Relatives and the US government say the three were innocent tourists on an adventure hike in northern Iraq and accidentally crossed into Iran, where they were arrested on July 31. “They will be tried by Iran's judiciary system and verdicts will be issued,” Mottaki said at a news conference, without elaborating in detail. He said the three were still being interrogated. The Americans — Shane Bauer, 27, Sarah Shourd, 31, and Josh Fattal, 27 — were detained by Iranian authorities after crossing an unmarked border from northern Iraq. They have been held in Iran's Evin prison, where Swiss diplomats have visited them twice and said they are healthy. Because the US and Iran do not have direct diplomatic relations, the Swiss Embassy maintains an American interests section. Meanwhile, Iranian authorities have arrested several people accused of destroying photos of the Islamic Republic's revered founder and the current supreme leader at student demonstrations, state media reported Monday. Tehran's prosecutor promised to show “no mercy” to those responsible, but the news reports carrying his remarks gave no details on those arrested. In demonstrations on university campuses last week, supporters of Iran's pro-reform opposition movement burned and trampled on pictures of Supreme Leader Ayatollah Ali Khamenei. They oppose him for backing President Mahmoud Ahmadinejad's disputed June re-election, which the opposition says was rigged.