Iranian President Mohammad Khatami has said Saddam Hussein is unlikely to receive a fair trial because he could reveal too many embarrassing details.
Iranians were 'hurt' by Saddam
"Saddam will undoubtedly make statements that will not be pleasing to many people among those who are now standing against Saddam," he said.
Iran - which was invaded by Iraq in 1980 - is preparing charges against the ousted Iraqi president.
Mr Khatami has said he does not "like the death penalty".
"But I believe if there is one case where there should be an execution, the fairest case would be for Saddam," the moderate cleric told reporters.
Iran's hardline judiciary frequently passes the death penalty.
It can be applied to convicted murderers, armed robbers, rapists, apostates and drug traffickers.
At least nine executions across the country have been reported by the Iranian media in the last week alone.
President Khatami said Saddam Hussein had hurt "many people," including many Iranians.
"What we want is an open trial for
Saddam, and that it should be fair," he said.
But he said he doubted that the trial of the former Iraqi leader would be "totally fair" because of the awkward details he could reveal.
The United States backed Saddam Hussein during the Iran-Iraq war, providing financial assistance and military intelligence.
After the 1979 Islamic revolution in Iran, the country was regarded by Washington as more dangerous than its neighbour Iraq.
Saddam Hussein was also supported by the Soviet Union, European nations and other Arab states.
BBC News Online world affairs correspondent Paul Reynolds says the French President Jacques Chirac and the US Defence Secretary Donald Rumsfeld might find their names in the frame.
In 1975, Mr Chirac - then prime minister - showed Saddam Hussein round a nuclear plant and later referred to him as "My dear friend".