Diplomats Say Provisional Iran Nuke Deal Likely Ready Sunday as U.S. Says 'Major Issues' Remain

Negotiators at the Iran nuclear talks are expected to reach a provisional agreement Sunday on a historic deal that would curb the country's atomic program in return for sanctions relief, diplomats said.

Two diplomats at the talks told The Associated Press the envisioned accord will be sent to capitals for review and, barring last-minute objections, be announced on Monday.

They spoke on condition of anonymity because they were not authorized to discuss the negotiations publicly.

The agreement would cap nearly a decade of diplomacy, including the current round in Vienna that has run more than two weeks and blown through three deadlines.

However, a U.S. official said later on Sunday that "major issues" must still be resolved in the talks.

"We have never speculated about the timing of anything during these negotiations, and we're certainly not going to start now -- especially given the fact that major issues remain to be resolved in these talks," the senior State Department official said.

Iranian diplomat Alireza Miryousefi, writing on Twitter, quoted a senior official from Tehran as saying a deal by Sunday night was "logistically impossible" as the agreement being drawn up spanned 100 pages.

The tortuous talks entered Sunday what France's foreign minister said he believed is the "final phase" but with Tehran warning that "political will" was still required.

"I hope we are finally entering the final phase of these marathon negotiations. I believe it," French Foreign Minister Laurent Fabius told reporters as he returned to Vienna on the 16th day of talks.

"A deal is in reach," agreed Iranian diplomat Alireza Miryousefi, adding however on Twitter on the eve of the latest effective deadline for an accord: "It only requires political will at this point."

Earlier, U.S. Secretary of State John Kerry, who has been locking horns with his Iranian counterpart Mohammad Javad Zarif in the Austrian capital since June 27, was hopeful but said that "tough" issues remained.

"I think we're getting to some real decisions. So I will say, because we have a few tough things to do, I remain hopeful. Hopeful," Kerry said, calling his latest meeting with Zarif "positive."

The talks are aimed at nailing down a deal curbing Iran's nuclear activities in order to make it extremely difficult for Tehran -- which denies any such aim -- to develop the atomic bomb.

In return Iran will be granted staggered relief from painful sanctions, although the six powers are insisting that they retain the option to reimpose the restrictions if Tehran violates the deal.

EU foreign policy chief Federica Mogherini who chairs the P5+1 group -- the U.S., Russia, China, Britain, France and Germany -- said Sunday on Twitter that these were the "decisive hours."

And a diplomatic source said Saturday as a flurry of bilateral and multilateral meetings went deep into the night that "98 percent of the text is finished."

Russian Foreign Minister Sergei Lavrov was meanwhile on his way to join the talks in Vienna, his ministry said.

- 'Time to decide' -

Under the parameters of a framework deal reached in Lausanne in April, Iran is to slash the number of its centrifuges from more than 19,000 to just over 6,000 and sharply cut its stocks of enriched uranium, which could be used for a bomb.

Negotiators left the thorniest issues until last, including a mechanism for lifting interlocking EU, U.S. and U.N. sanctions.

A new hurdle was thrown up in recent days, with the Iranian delegation insisting that a U.N. arms embargo be lifted once a deal is reached.

The talks have also stumbled over demands to allow U.N. nuclear inspectors access to military sites, to investigate suspicions Iran sought to develop nuclear weapons in the past.

A final agreement would be a diplomatic victory for U.S. President Barack Obama, who has made the talks a centerpiece of his foreign policy, and for his Iranian opposite Hassan Rouhani, a moderate seeking to end his country's diplomatic isolation.

Both have faced opposition from hardliners at home, as well as from Iran's arch-foe Israel, believed to be the Middle East's only nuclear-armed state, although it has never confirmed it.

Israeli Prime Minister Benjamin Netanyahu said Sunday that the deal would allow Iran to make "many nuclear bombs and gives it hundreds of billions of dollars for its terrorism and conquest machine."

Saudi Arabia and other Sunni-ruled Gulf Arab states are also deeply suspicious of Shiite Iran, accusing it of fomenting unrest in Syria, Yemen and other flashpoints.

Obama, a Democrat, has faced persistent opposition to his Iran policy from U.S. Congress, controlled by Republicans, who in a 60-day review period may try to scupper the accord.

Iran has for years faced U.N., EU and U.S. sanctions that have placed restrictions on the country's oil and banking sectors, trade and everyday life for the 78 million population.

In Tehran, Iran's supreme leader Ayatollah Ali Khamenei said Saturday that the battle against the "arrogance" of the United States would continue even if there is a deal.

"This is an historic moment and there could be serious repercussions if negotiators fail to seize this opportunity to get a good deal," Arms Control Association analyst Kelsey Davenport told AFP.