Washington, Jun 13 (DPA): Iran's leaders must respect the rights of their citizens and uphold the country's international obligations, the United States said Saturday, on the first anniversary of the Islamic republic's disputed presidential election.

US Secretary of State Hillary Rodham Clinton called for the immediate release of imprisoned human rights activists as well as three American hikers who have been detained for almost a year without being charged.

A year after thousands of Iranians took to the streets to protest the election results, to which the government responded with violence and arbitrary detentions, many political prisoners continue to languish in jail, some facing death sentences for expressing their opinions.

"The Iranian government's denial of the fundamental freedoms and rights accorded to its citizens in the Iranian constitution and international treaties to which Iran is a party has drawn broad international condemnation," Clinton said in a statement.

Iranian President Mahmoud Ahmadinejad was re-elected in the June 12, 2009 vote amid widespread accusations from the opposition of electoral fraud.