US President Barack Obama has called on Iran to free three American hikers it detained one year ago.

He also said that Sarah Shourd, Shane Bauer and Josh Fattal never worked for the U.S. government and were people who have demonstrated open-mindedness and a desire for social justice.

According to Politico, Iran recently charged the three young University of California Berkeley graduates with having improperly crossed the border, while it continues to carry out an investigation.

But it did not charge them with espionage, as it had previously threatened.

Obama also called on Iran to provide information in the case of former FBI agent Robert Levinson, who went missing after a 2007 meeting on Kish Island.

"Sarah, Shane and Josh committed absolutely no crime. Yet for a full year, they have been held in prison, causing extraordinary grief and uncertainty for them, for their families, and for their loved ones," Obama said in a statement.

"I want to be perfectly clear: Sarah, Shane and Josh have never worked for the United States government. They are simply open-minded and adventurous young people who represent the best of America, and of the human spirit. ...They have never had any quarrel with the government of Iran, and have great respect for the Iranian people," he added.

"I call on the Iranian government to immediately release Sarah, Shane and Josh. Their unjust detention has nothing to do with the issues that continue to divide the United States and the international community from the Iranian government," Obama said.

Obama also acknowledged the suffering and advocacy of the families, and said he had spoken with the hikers' mothers and Levinson's wife this week.

Secretary of State Hillary Clinton also put out a statement Friday calling the hikers' release "long overdue" and their continued detention "unjustifiable." (ANI)