In July, three American backpackers were detained in Iran and charged with illegally crossing the boarder from Iraq. On Monday, a Tehran prosecutor announced that the three are being charged with spying.

The announcement of the charges comes only days after U.S. Secretary of State Hillary Clinton met privately with the families of Shane Bauer, Sarah Shourd and Josh Fattal, who family say crossed the border by mistake. Their family and friends say it was an innocent mistake.

Clinton on Thursday repeated a call to the Iran government to release the hikers on humanitarian grounds. "As a mother my heart went out to all of them. I cannot imagine what it would feel like to know that your child was in prison for now 100 days with very little contact between you and them," she said.

"I told them that we are doing everything we possibly could to get Shane and Joshua and Sarah home. And we are exploring every angle. Obviously I would hope that the government of Iran would free them on humanitarian and compassionate basis and return them to their families," she said.

The United States, which has no diplomatic relations with Iran, has relied on Switzerland to appeal directly for the hikers' release. A Swiss diplomat has met twice with the Americans in their Iranian prison. The Swiss diplomats took clothes and other supplies, including books and writing papers, to the Americans.

"We were informed via the State Department that Shane, Sarah and Josh are in good physical shape and we're obviously happy they received another visit," the families said in a written statement. "Today marks exactly three months since our children were detained and we urge the Iranian authorities to let our children speak to us directly. Every time our telephones ring, we hope they it is them calling to tell us they've been released."

A senior State Department official told CNN that it was reported the three seemed to be nervous and scared, but also appeared to be in good physical and psychological health.

The three young Americans, all graduates of the University of California at Berkeley, were in a peaceful region of Iraq that is increasingly popular with Western tourists, when they apparently crossed onto Iran territory.

Friends say Shane, Josh and Sarah share a love for culture and travel. It was this love that brought them to Kurdistan.

What can you do?

Become a fan of the FreetheHikers page on Facebook to keep up to date on news related to the three and the protests and vigils being held around the world.