Iran's leaders have welcomed a landmark nuclear agreement with world powers, calling it a recognition of Iranian nuclear rights and the beginning of an end to international sanctions.
In a televised address Sunday, Iranian President Hassan Rouhani said the interim deal reached early Sunday in Geneva recognizes what Iran says is its "right" to enrich uranium.
Iran says its enrichment work is for peaceful purposes. But Israel and Western powers fear Iran could enrich its uranium to the high purity needed to develop nuclear weapons.
U.S. Secretary of State John Kerry denied Iran's interpretation of the deal reached with Washington and five other world powers. He told reporters in Geneva the document "does not say Iran has a right to enrichment."
The six-month agreement calls for Iran to neutralize its stockpile of uranium enriched to 20 percent - a level that is a short step away from weapons-grade. But it allows Iran to continue enrichment below the five percent level.
The deal also calls for Iran not to make further advances in building a heavy water nuclear reactor in the city of Arak. Once operational, the facility could produce plutonium, another compound used to make nuclear weapons.
Earlier, U.S. President Barack Obama said the Geneva agreement will place "substantial limitations" on Iran's enrichment and "cut off" what he called the nation's "most likely paths to a bomb." He said the deal is a "first step" toward negotiations aimed at fully addressing international concerns about the Iranian nuclear program.
In return for limiting enrichment, the five permanent members of the U.N. Security Council plus Germany agreed to temporarily lift some international sanctions that have weakened the Iranian economy.
The United States says Tehran will gain access to $4.2 billion in revenues from Iranian oil exports and $1.5 billion in proceeds from Iranian sales of precious metals, autos and petrochemicals.
Iranian leaders hailed the deal as the start of a process of ending years of sanctions imposed by the U.N. Security Council and Western powers in retaliation for Iran's refusal to suspend enrichment.
Iranian state media quoted Supreme Leader Ayatollah Ali Khemenei as saying the agreement is a "success" attributed to "the grace of God and the prayers of the Iranian nation."
But in an interview with CNN, Secretary Kerry said the concessions made by the world powers give "very little relief" to Iran.
Israel, a key U.S. ally in the Middle East, denounced the deal. Speaking Sunday to the Israeli Cabinet, Prime Minister Benjamin Netanyahu called the agreement a "historic mistake," saying it marks the first time the international community has "formally consented" to Iran continuing its enrichment.
Mr. Netanyahu said Israel is "not bound" by the deal and "will not allow Iran to have a nuclear weapons capability." Israeli leaders see a nuclear-armed Iran as a threat to their nation's existence because of Iran's frequent calls for Israel's demise.
The United States and Israel have said they prefer a diplomatic solution to the Iranian nuclear dispute, but they also have not ruled out military action if diplomacy fails.
A senior U.S. official told Western news agencies that the Geneva agreement followed several months of secret bilateral talks between the United States and Iran. In comments published Sunday, the U.S. official said the talks were aimed at developing ideas to complement official negotiations involving Iran and the world powers.
The Associated Press quoted U.S. officials as saying Deputy Secretary of State William Burns began leading the secret meetings with Iranian officials in March, using Oman and other locations as venues. It said the talks intensified after Iranian President Rouhani took office in August.
President Obama's Republican critics in Congress criticized the nuclear deal, saying it rewards Iran without forcing the nation to dismantle facilities that could be used for nuclear weapons.
Some Republican Senators said Congress may adopt tougher sanctions in six months if Iran does not abide by the terms of the Geneva deal.