Mehdi Karroubi and Mir Hassa Mousavi have been under house arrest since 2011 because of their role in the mass protests that rocked the Iranian regime two years earlier.
"I ask the Supreme Leader to intervene to ensure that the issue of house arrest is resolved," Khatami said. "The responsible institutions can not and will not resolve the issue of house arrest, and only your intervention can allow this issue to be resolved.
Khatami, the reformist president, took the presidency between 1997 and 2005 and has been banned from appearing in the media since the protests. The case was brought to the fore after Karubi, 79, briefly dined on Wednesday, demanding his trial, while his hunger strike was suspended the next day after he was reportedly Assurances from the government that at least the newly released intelligence agents will be taken out of his home.
Karrubi and Mousavi were candidates in the disputed 2009 presidential election, accusing the regime of forging the result for hardliner Mahmoud Ahmadinejad.
Karubi's death is feared to lead to new protests, although he was hospitalized several times last month and underwent cardiac surgery.