By Sadeq Saba
BBC News regional analyst
The Council has blocked women from running for the office
The decision to disqualify all credible reformist and liberal candidates may have serious internal and international consequences for the Islamic republic.
Iranian television has announced that only six out of more than 1,000 candidates for the forthcoming presidential elections have been endorsed by the hardline watchdog body, the Guardian Council.
Several well-known reformist politicians were among those disqualified, including the former education minister, Mostafa Moin.
The only remaining reformist candidate on the approved list is the former speaker of parliament, Mehdi Karrubi - but he is not their main contender.
Those who are rejected have the right to appeal to the same body to reinstate them.
The largest pro-reform party, the Participation Front, has already threatened to boycott the elections if its candidate is not reinstated.
Most Iranians, who are disappointed with the slow pace of reform, were not showing much interest in the presidential elections before this decision. Now the Islamic government may face the prospect of an embarrassingly poor
Human rights activists may also accuse the ruling clerics of holding a poll which does not meet the international standards for free and fair elections.
Some student groups and many intellectuals have already called for a referendum on the future of the Islamic republic.
They say the president in Iran's clerical system of government has little power.
At a time when the Islamic republic is under increasing European and US pressure for its controversial nuclear activities, the decision to allow only a handful of mainly hardline candidates to stand may add to Iran's problems with the international community.