A top Iranian army commander warned reformist presidential candidate Mehdi Karroubi on Monday against accusing the Islamist Basij militia of electoral interference, the state IRNA news agency reported.

"Although in the previous election, Karroubi and some other candidates repeatedly made this claim ... they have not been able to present a shred of evidence," armed forces deputy chief of staff Masoud Jazayeri said.

"It is deplorable that he does not stop his propaganda," Jayazeri added, warning that "the Basij and the armed forces maintain the right to challenge those who spread lies through the courts."

Karroubi blamed his defeat by hardliner Mahmoud Ahmadinejad in the last presidential election in 2005 on what he called "bizarre illegal interference" by the Basij militia and the Revolutionary Guards.

The cleric is standing again against Ahmadinejad in Friday's election along with moderate former premier Mir Hossein Mousavi and conservative former Guards chief Mohsen Rezai.

He has urged both the authorities and supreme leader Ayatollah Ali Khamenei to ensure there is no repeat of the experience of 2005.

Formed by order of Iran's revolutionary leader Ayatollah Ruhollah Khomeini soon after the 1979 overthrow of the US-backed shah, the Basij volunteers won renown for mounting "human wave attacks" on Saddam Hussein's forces during the 1980-88 war with Iraq.

Reported to have hundreds of thousands of members, the militia has a military wing which forms part of the ground forces of the Revolutionary Guards.