A British daily reported that Iran's Guardian Council, a constitutional watchdog run by senior clerics, would seek possible charges against the president, after he accompanied his chief of staff Esfandiar Rahim Mashaei when Mashaei registered as a candidate for Iran's June 14 presidential election.
The Council claims that by doing so, Ahmadinejad tried to promote his protégé Mashaei as his successor. Iran's constitution bans the incumbent president from supporting a successor.
Footage of the two men together during Mashaei's registration was broadcast by Iranian state television. If convicted, Ahmadinejad could face 74 lashes or six months behind bars, the British daily said.
However, according to the official IRNA news agency, spokesman Gholam-Hossein Elham said the president did not break election rules as he attended the registration of candidates as an individual and not as the country's leader.
Elham also claimed that according to the law, the election campaign in Iran only officially starts after candidates are approved by the Guardian Council.
A total of 686 candidates have registered for Iran's forthcoming presidential election, the country's Interior Minister Mustafa Mohammad-Najjar said.
Among them is former president Akbar Hashemi Rafsanjani, 78, a leading reformer.
The Guardian Council is expected to decide on the eligibility of candidates by May 23. The official election campaign will end June 12.
The Iranian president is elected for a four-year term in a national election.
Ahmadinejad is not running, as the constitution bars him from seeking a third term in office.