Gaps remain as Iran nuclear talks near deadline

Negotiations over Iran's nuclear program entered a critical phase Monday with differences still remaining less than two days before a deadline for the outline of an agreement.

Ahead of the midnight March 31 target, top diplomats from the five permanent members of the U.N. Security Council along with Germany (collectively known as P5+1) and Iran were meeting to try to bridge remaining gaps and hammer out the framework deal that would be the basis for a final accord to be reached by the end of June.

The six powers want a 10-year suspension of Iran's most sensitive uranium enrichment work, to prevent it from having the capability, if so desired, to build a nuclear weapon within a one-year timeframe. Tehran, which has always denied trying to develop nuclear weapons, demands in exchange for limits on its atomic activities a swift end to international sanctions that are crippling its economy.

Despite signs from both sides that they are willing to compromise, officials at the talks with Iranian Foreign Minister Mohammad Javad Zarif in the Swiss city of Lausanne on Monday cautioned that attempts to reach a framework accord could yet fall apart.

German Foreign Minister Frank-Walter Steinmeier said there had been "some progress and some setbacks in the last hours.”

"I can't rule out that there will be further crises in these negotiations," he told reporters in Lausanne.

In addition to Steinmeier, other foreign ministers present at the meeting include the U.S.’s John Kerry, Britain’s Philip Hammond, France’s Laurent Fabius, Russia’s Sergei Lavrov and China's Wang Yi. Lavrov returned to Moscow on Monday, indicating that a deal was unlikely that day. But a spokeswoman for the Russian foreign minister said he would return Tuesday if there was a realistic chance for a deal. 

Officials said the talks could run up until the deadline of midnight on Tuesday. If a framework agreement is reached in Lausanne, the leaders may relocate to Geneva for a ceremony.

While some issues being discussed in the negotiations have been resolved, there are several key differences on which the two sides have yet to agree.

One sticking point concerns Iran's demand to continue with research into newer generations of advanced centrifuges that can purify uranium faster and in greater quantities than the ones it currently operates for use in nuclear power plants. Another concerns how quickly the United Nations would lift sanctions on Iran if a deal is struck.

A senior U.S. official said on Sunday there were other unresolved issues, but expected those would fall into place if the big sticking points could be worked out.

Even if Iran and the six powers reach a framework agreement by their March deadline, officials close to the talks say it would be very preliminary and could still fall apart when the two sides attempt to agree on all the technical details for a comprehensive accord by June 30.

Al Jazeera and wire services