Iran's supreme leader has ordered the Guardian Council to reconsider a ruling barring two reformists from standing for the presidency.
Ayatollah Khamenei said voters should be offered a choice
State TV said Ayatollah Ali Khamenei had written to the council instructing it to reconsider the applications of Mostafa Moin and Mohsen Mehr Alizadeh.
The council rejected the applications of all but six of more than 1,000 candidates for the 17 June poll.
Reformists said the move was illegal and called for a boycott of the vote.
The Council of Guardians vets all candidates for their moral values and support for the country's system of Islamic government.
Parliamentary polls last year were also mired in controversy after the Council barred about 2,500 reformist candidates.
However, Ayatollah Khamenei - as supreme leader - has overall authority in all political and spiritual matters and appoints the members of the Guardian Council.
Choice for voters
"It's appropriate that all individuals in the country be given the choice from various political tendencies," Iranian TV quoted him as saying in his decree to Ayatollah Ahmad Jannati, head of the Council.
"Therefore, it seems that the competence of Mr Moin and Mr Mehr Alizadeh to stand should be reconsidered."
Mostafa Moin described his disqualification as "unfair and illegal"
Earlier on Monday, Mr Moin, a former education minister and the favoured candidate of the Islamic Iran Participation Front (IIPF), described his disqualification as "unfair, unreasonable and illegal".
Mostafa Tajzadeh, a senior IIPF member, told AFP: "I think the elections should be boycotted. This is definitely a coup d'etat."
Mr Mehr Alizadeh is currently a vice president in the cabinet of outgoing President Mohammad Khatami. Mr Khatami is barred by law from seeking a third consecutive term.
Former president and election favourite Akbar Hashemi Rafsanjani, four conservatives and a reformist make up the approved field of candidates.
The four hardliners are a former police chief, a former commander of revolutionary guards, the mayor of Tehran and a former head of state radio and television.
Iran's former parliamentary speaker Mehdi Karrubi remains on the list, but correspondents say he had not been the reformists' main contender.