Incumbent Iranian President Mahmoud Ahmadinejad has focused his attacks on former presidents Mohammad Khatami and Akbar Hashemi Rafsanjani.
During a televised debate with his rival Mir Hossein Mousavi, President Ahmadinejad accused the two Iranian figures of masterminding a plot to push him out of power.
He underlined what he believed were examples of mismanagement and corruption during the two president's administrations.
Mousavi in response attacked Ahmadinejad for accusing the people who did not have a representative in the debate, saying the tactic was adopted by the incumbent President because Ahmadinejad had not found anything against him.
Mousavi also slammed Ahmadinejad for ignoring the legal principle of the presumption of innocence through accusing those who were not convicted in a court.
Elsewhere, he touched on the issue of Ali Kordan, the former interior minister who was impeached by the Parliament (Majlis) over his fake academic degree and said Ahmadinejad still supported him.
Ahmadinejad said many officials under Rafsanjani and Khatami acquired fake academic degrees and his support had nothing to do with Kordan's degree.
He also accused Zahra Rahnavard, Mousavi's wife of studying in universities while she was a government employee to receive two masters degrees and obtaining her doctorate without an entrance exam.
Mousavi, however, said Rahnavard had studied for ten years to receive a doctorate and hit back at Ahmadinejad for adopting "an immoral strategy" by his move.
Iran's presidential election will be held on June 12. President Ahmadinejad, Mousavi, former parliament speaker Mahdi Karoudi and Secretary of Iran's Expediency Council Mohsen Rezaei are the candidates.
