No details have been released, but Mr Khatami is believed to have expressed his deep concern about the way the body screened candidates for the Assembly of Experts, a clerical council which has the power to appoint and dismiss Iran's supreme leader - currently Ayatollah Khamenei.

President Khatami is also reported to have had emergency talks with Ayatollah Khamenei on the issue.

Moderates 'furious'

Moderate groups are said to be furious the conservatives have used their influence in the election supervisory body - the Guardian Council - to disqualify almost all of their candidates, including some prominent clerics.

Ayatollah Khamenei is the figurehead for the conservative establishment

The BBC Iranian Affairs analyst Sadeq Sabab says they were hoping to enter the powerful Assembly of Experts in an attempt to make it more democratic.

Excluded candidates have accused the council of being partisan.

Our correspondent says if President Khatami fails to persuade the election body to reinstate at least some of the candidates, there could be a widespread boycott of the elections.