TEHRAN, Iran -- Under pressure from Iran's supreme leader, the country's hard-line watchdog reversed itself Tuesday and said two reformist candidates can run in next month's presidential race -- defusing a brewing crisis that had sparked fears of a boycott.

The move by the Guardian Council came as Iran's clerical rulers seek a high turnout to boost their credibility at a time when the country remains under intense international pressure over its nuclear program.

Low turnout in the June 17 election could undermine the ruling Islamic establishment at home and weaken its position in crucial negotiations with Europeans over the controversial nuclear program.

"A president elected with the least votes will not be able to pursue the people's demands and defend Iran's rights at the international level," Interior Ministry spokesman Jahanbakhsh Khanjani told reporters Tuesday.

But the council's decision is unlikely to appease reformists, who have called its vetting policies illegal.

About 48 million Iranians are eligible to vote, and according to some private surveys, only half of them will go to the ballot box.

Iran is at a crucial juncture in its history, having achieved proficiency in nuclear technology. The country says it now controls the whole nuclear fuel cycle -- from extracting uranium ore to enriching it, a sensitive technology that can produce nuclear fuel to generate electricity or a nuclear weapon.

Europeans have threatened to take Iran to the U.N. Security Council for possible economic sanctions if it restarts uranium-reprocessing activities. Washington backs a tough line and accuses Tehran of using its civilian nuclear program as a cover to build nuclear weapons.

On Sunday, Khamenei, who has the final say on all state matters, had ordered the Guardian Council to review its earlier ban on some of the reformist applicants. Although no organized calls for a boycott had emerged, the supreme leader was believed to be concerned about a low turnout.

The council, controlled by hard-liners loyal to Khamenei, had rejected all reformists who registered to run in next month's presidential elections, approving overall just six out of more than 1,000 hopefuls.

Moin and Mohsen Mehralizadeh, the vice president in charge of sports, were the two most prominent reformists who had been barred from running, and were the two approved on Monday to be allowed to run, television reported Tuesday.

The council's decision was made public in a letter sent Tuesday by Guardian Council chief Ayatollah Ahmad Jannati to Khamenei. In the letter, Jannati defended the council's ban on reformists and said the approval of Moin and Mehralizadeh came in an emergency meeting called Monday after Khamenei's instructions.

"On the basis of regulations and laws, (the council) held detailed discussions and studied necessary documents and background facts," Jannati said in the letter.

President Mohammad Khatami -- a reformer barred by law from seeking another term -- said he was pleased with Khamenei's intervention and that the move prevented damage to the country.

Hard-liners consider Khamenei above the law and believe he is answerable only to God. Questioning or criticizing Khamenei is punishable by jail. He stands above factional politics but has mostly supported hard-liners against reformers.

Ruling clerics led by Khamenei are seeking to consolidate power after the departure of Khatami.

The front-runner is powerful former President Hashemi Rafsanjani, who moves frequently between the hard-line and more moderate camps.

Other approved candidates include former national police chief Mohammad Bagher Qalibaf; former radio and television chief Ali Larijani; Tehran Mayor Mahmoud Ahmadinejad; former head of the elite Revolutionary Guards Mohsen Rezaei; and former parliamentary speaker Mahdi Karroubi.

Qalibaf, Rezaei, Larijani and Ahmadinejad are widely seen as Khamenei candidates because of their strong loyalty to him.

Karroubi has some support among reform-minded voters loyal to the clerical establishment, including one-time hardline clerics who have moderated their views. But he is unpopular among young Iranians who make up the majority of Iran's 70 million population and are more inclined toward sweeping reforms.

Moin, a respected university professor, is the sole candidate of Iran's largest reformist party, the Islamic Iran Participation Front and enjoys popularity among Iran's predominantly young population.

Mehralizadeh has similar political views but does not have as large a following as Moin does.