Iranian opposition leaders Mir Hossein Mousavi and Mehdi Karroubi have issued a proposal calling for constitutional change.
The "reform charter" states, among other things, that civil codes, including the constitution, are not meant to last forever and can be changed. It also calls on the Iranian government to respect the legal status of minorities.
The charter was posted Tuesday on Mousavi's website Kaleme.com. Iranian state media have not responded to the proposals.
This latest initiative by Iranian opposition leaders comes as protesters across the Middle East and North Africa have called for reforms, with demonstrators toppling leaders in Tunisia and Egypt.
While Iran routinely cracks down on opposition, it has issued statements in recent days encouraging protesters in neighboring nations.
Iranian President Mahmoud Ahmadinejad said Wednesday that Arab leaders must listen to their people and questioned how leaders could use violence against their citizens.
Iranian authorities violently dispersed an opposition rally earlier this month. The clashes killed at least two demonstrators.
Also Wednesday, the U.S. Treasury and State Departments blocked the assets of two Iranian officials deemed responsible for or complicit in serious human rights abuses in Iran.
The Treasury Department said U.S. citizens are also prohibited from engaging in transactions with Tehran Prosecutor General Abbas Jafari Dolatabadi and Mohammed Reza Naqdi, commander of the Islamic Revolutionary Guard Corps' Basij militia.