An unprecedented power struggle at the heart of the Iranian regime has intensified after it emerged that the supreme leader, Ali Khamenei, had given an ultimatum to President Mahmoud Ahmadinejad to accept his intervention in a cabinet appointment or resign.

A member of the Iranian parliament, Morteza Agha-Tehrani – who is described as "Ahmadinejad's moral adviser" – told a gathering of his supporters on Friday that a meeting between Ahmadinejad and Khamenei had recently taken place, in which the president was given a deadline to resign or to accept the decision of the ayatollah.

The extraordinary confrontation came to light after Ahmadinejad declined to officially support Khamenei's reinstatement of a minister whom the president had initially asked to resign.

The rift between the two men grew when the president staged an 11-day walkout in an apparent protest at Khamenei's decision. In the first cabinet meeting since ending his protest, the intelligence minister at the centre of the row, Heydar Moslehi, was absent and in the second one on Wednesday, he was reportedly asked by Ahmadinejad to leave.