WASHINGTON - Fusing the piety of Islam with the celebrity of boxing champ Muhammad Ali, the mothers of American hikers Josh Fattal and Shane Bauer today beseeched Iran to release their sons after 22 months in prison.

The pair have been imprisoned in Tehran on charges of entering the country illegally to commit espionage.

Against a banner emblazoned "662 Days Without Freedom" - and with a mute but imposing Ali in dark glasses to their right - Laura Fattal, of Elkins Park, and Bauer's mother, Cindy Hickey, of Minnesota, said the charges against their sons are baseless.

"Shane and Josh are innocent and have suffered long enough," said Hickey, her voice thick with emotion. "Life has continued on around us while we remain frozen in time."

Said Fattal: "Iran's indecision and delay have taken a terrible toll - on them and on us."

But an Iranian Foreign Ministry official hinted today the prosecution of the two would proceed, saying that calling them hikers was a "joke," according to the Associated Press.

The mothers were surrounded by leaders of the Islamic Society of North America, the Muslim American Society Freedom Foundation, the Universal Muslim Association of America and the Council on American Islamic Relations, who in a letter to Iran's Grand Ayatollah Ali Khamenei asked for "compassion and mercy."

"After listening to the families, we believe that these Americans did not seek to cause any problems between the United States and the Muslim world . . . but were in the region for the opposite purpose, to promote dialogue and understanding," the letter said.

Fattal, an environmentalist, and Bauer, a photojournalist, both 28, were trekking on vacation in northern Iraqi Kurdistan when they were arrested by Iranian border guards on July 31, 2009. Also arrested with them was Sarah Shourd, 32, a language teacher, who is engaged to Bauer. The three started their trip from Damascus, Syria, where Bauer and Shourd were living.

Shourd, who spent more than 400 days in solitary confinement and had medical problems, was released in September on $500,000 bail.

"Josh and Shane have now been imprisoned for eight months longer than I was," Shourd said, addressing a crowded news conference at the National Press Club. "Their detention has everything to do with the animosity between the United States and Iran and nothing to do with two innocent men who have always stood on the side of what's right."

Ali, who will turn 70 in January, came to Washington from his home in Scottsdale, Arizona.

Speaking for her husband, whose Parkinson's disease inhibits his speech, Lonnie Ali said the hikers reminded him of himself as a young man, "a citizen of the world . . . who wanted to experience other cultures. That's a good thing."

Ali, who as a young boxer converted to Islam, is a worldwide icon and widely liked in Iran.

"They love this man," said his wife, calling on Iran to release the hikers, "for the love of Allah and the love of Muhammad."

Later, in an interview, she said, "Muhammad would leave in a second if he thought it would bring these boys home."

The drawn out trial of the hikers was delayed again on May 11, after authorities, without explanation, did not bring them to court for a scheduled hearing. No new trial date was set.