U.S. Secretary of State John Kerry speaks during his final press conference after talks over Tehran's nuclear program in Vienna, Austria, on July 15. / Joe Klamar, AFP/Getty Images
Corrections and Clarifications: An earlier version referred to Iran as Iraq in the first paragraph.
Secretary of State John Kerry on Tuesday cited "very real gaps" between world powers and Iran over details of a proposed nuclear agreement.
Kerry, in Vienna for three days of talks, rejected a proposal from Iran Foreign Minister Mohammad Javad Zarif that Iran could maintain its current number of nuclear enrichment centrifuges as part of a long-term deal leading to a gradual end of sanctions. But Kerry added that progress has been made.
"We have all kept the commitments made in the joint plan," Kerry said. "And we have all lived up to our obligations. We have all continued to negotiate in good faith. But after my conversations here ... it is clear that we still have more work to do."
Zarif told Iran's Islamic Republic News Agency that he had a good exchange of views with Kerry.
The talks were crucial as Sunday's deadline for a nuclear deal nears. The foreign ministers of Germany, France and Britain joined the Vienna talks in an effort to hammer out a deal. Noticeably absent: Russia and China.
"Despite the difficulties of these negotiations, I am confident that the United States and our partners remain as squarely focused as ever on testing whether or not we can find a negotiated solution to this most pressing international security imperative," Kerry said.
Kerry was scheduled to return to Washington on Tuesday to consult with President Obama and Congress about the state of negotiations. He said he will also discuss the possibility of extending the talks past the deadline. The parties have been operating under a temporary, six-month agreement that took effect Jan. 20.
Israeli Prime Minister Benjamin Netanyahu opposes any accord that lets Iran continue to enrich nuclear fuel. "What Iran is seeking is to keep the materials and the means to make nuclear weapons, and just allow inspections," Netanyahu warned last month. "Keep and inspect, rather than dismantle and remove - that's the bad deal."
Iran says it needs to produce fuel for a nuclear power plant built by Russia and other plants it plans to build. The process also can be used to produce fuel for bombs. Despite Iran's claims that its program is peaceful, the United States, Israel and other nations suspect Iran of hiding a secret weapons program.
About half of Iran's 19,000 centrifuges are operating. Before November's interim agreement that slowed its program, the U.S. estimated that Iran could produce enough highly enriched uranium for a bomb in a month or two. That so-called breakout time has been doubled under the temporary agreement.
Contributing: Eve Chen and Oren Dorell, USA TODAY; Associated Press
Copyright 2014USA TODAY
Read the original story: Kerry warns of 'very real gaps' in Iran nuclear talks