TEHRAN, Iran - Iran's intelligence minister accused three Americans jailed since crossing the border from Iraq in July of having links to U.S. intelligence services, state TV reported Thursday.

The comments toughened Iran's accusations against the group, suggesting authorities could be close to bringing them to trial after months of mixed signals and fears in the U.S. that they could be used as bargaining chips in Iran's confrontation with the West.

Their families say the three were on a hike in the scenic Kurdish region of northern Iraq and unintentionally strayed across the border. Iran has accused them of spying and said it intends to bring them to trial.

Iran's English-language satellite channel Press TV said Intelligence Minister Heidar Moslehi told the station in an exclusive interview that Tehran has "credible evidence" the three were linked to U.S. intelligence. He did not elaborate but said the evidence would be revealed to news media soon.

It was the first time a senior official has said the three were tied to U.S. intelligence.

Moslehi also warned neighboring countries against cooperating with U.S. and Israeli intelligence, the report said.

Press TV briefly showed footage of the minister speaking but did not air his comments in full. Instead, a news anchor read out a summary of the main points.

In Washington, State Department spokesman P.J. Crowley said he was not aware of the specific allegation but flatly denied the trio had anything to do with U.S. intelligence.

"It's not true," he told reporters, without elaborating.

Josh Fattal, 27, Shane Bauer, 27, and Sarah Shourd, 31, were trekking in Iraq's northern Kurdistan region on July 31 when they accidentally crossed the border into Iran, according to their families.

Foreign Minister Manouchehr Mottaki said in December that he expected a speedy trial for the three.

President Mahmoud Ahmadinejad has questioned the Americans' intentions but said he would do his best to free them.

In November, however, Ahmadinejad said the United States was holding several Iranian citizens, raising concern that his government might be seeking to use the Americans in a deal.

The hikers' parents and U.S. Secretary of State Hillary Rodham Clinton have appealed for their release.

The continued detention of the Americans comes amid a bitter standoff between the U.S. and Iran over Tehran's disputed nuclear program.

The U.S. has no diplomatic relations with Iran. The last word on the Americans' conditions came in March when they called home, their families said.