Updated

President Obama marked the first anniversary of Iran's jailing of three young Americans by reiterating that they are guilty of nothing, have never worked for the U.S. government and never had any quarrel with the Iranian government.

In an appeal for Tehran to free Sarah Shour, 31, Shane Bauer, 28, and Josh Fattal, 28, Obama reminded Iran that it is a signatory to conventions on human rights that if honored would free the Americans.

"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's statement said. "This is a humanitarian imperative."

They were arrested last July 31 as they hiked along the Iraq-Iran border. Iran contends they are spies for the United States.

Obama's statement said he particularly wanted to "acknowledge the suffering and advocacy of Sarah, Shane and Josh

s families." He said he spoke this week with the captives' mothers, whom the Iranians allowed to visit their children briefly in May.

"The Iranian government

s gesture of allowing these mothers to visit their children was welcome, but I cannot imagine how painful it was for these three courageous women to return home without their children," Obama said in his statement.

"I told these three mothers that Sarah, Shane and Josh are in my thoughts and prayers, and that the U.S. government would continue to do all that it could to secure their release."