Mahmoud Ahmadinejad could face 74 lashes or six months in jail if punished to the full extent of the law for breaking electoral rules by accompanying his chief of staff to register as a candidate in Iran's forthcoming elections.
Iranian presidential candidate Esfandiar Rahim Mashaie with President Mahmoud Ahmadinejad in Tehran
Footage of a smiling Mr Ahmadinejad accompanying Esfandiar Rahim Mashaei to the electoral registry was broadcast on State television on Saturday.
In an off-guard moment, the Iranian president was caught apparently muttering to his aid and confidant that if questions were raised as to why he had accompanied him to the electoral registry, "tell them I'm on a day off work".
The Guardian Council complained about the president's conduct on Sunday. Iran's constitutional watchdog has said it might seek charges against Mr Ahmadinejad.
The Council's members said that public fund rules were broken when Mr Ahmadinejad accompanied Mr Mashaei to the election registration office.
The Guardian Council is charged with vetting all 680 hopeful presidential candidates, including Mr Mashaei.
Mr Ahmadinejad, who is constitutionally forbidden from running for a third term, has pushed hard for Mr Mashaei to succeed him when the country heads to the polls on June 14th in a campaign his opponents claim has been funded with public money.
The men have a close political bond, cemented by the marriage of their children.
However, Mr Ahmadinejad's long-standing feud with Iran's Supreme Leader Ayatollah Ali Khamenei and the ruling clerics is working against the presidential hopeful and undoubtedly played a role in Sunday's complaint against him.
Mr Mashaei, who announced his intention to run for the presidency on 11 May, has been accused of the Ayatollah's allies of seeking to undermine Islamic rule and criticised for his "deviant" tendencies.
Mr Mashaei, described as a "religious-nationalist", has outraged Iranian Islamic conservatives with his nationalistic and allegedly pro-Israel position.
He once stated that Iranians are "friends of all people in the world – even Israelis".
The cards for the June 14 elections have so far been stacked heavily in favour of candidates allied with the Ayatollah.
Among the current favourites are Mohammad Bagher Qalibaf, the mayor of Tehran and former police chief, and Ali Akbar Velayati, a senior adviser to the Supreme Leader.
Akbar Hashemi Rafsanjani, who was president for eight years between 1989 and 1997, has also launched his bid for a political comeback at the age of 78.