The Vienna talks on a possible return to the nuclear deal with Iran will take longer than originally estimated.
On Wednesday the negotiators adjourned to next week.
Confidence about the state of the negotiations was expressed from several delegations, but it did not seem possible to reach an agreement by Sunday.
Stephan Löwenstein
Political correspondent based in Vienna.
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Then an agreement between Iran and the International Atomic Energy Agency (IAEA) to control its nuclear activities will expire.
Evidently negotiators from the powers that be at the table - the E3 group of Germany, France and Great Britain, as well as Russia and China - have put pressure on Iran to extend the IAEA agreement to make room for talks to continue.
A representative of the European Union presiding over the talks said there had been "good progress". "An agreement is taking shape."
The Russian delegation also found an agreement "within reach". European diplomats said they were beginning to see "the outline" of a possible understanding. "That was different the last time we parted."
Nevertheless, success is not certain, difficult questions still have to be solved.
Iranian Deputy Foreign Minister Abbas Araghji said there had been "good progress". Delegations must now return to their capitals for consultations to resolve the remaining key issues.
In Vienna, the aim is to bring the 2015 nuclear agreement (JCPOA) back into force.
It was initially left by the United States, and the former President Donald Trump has imposed numerous sanctions on Iran since 2018.
Then Iran began violating the JCPOA's provisions that are designed to limit the nuclear program so that the regime cannot acquire nuclear weapons.
Iran denies a military purpose of its nuclear program.
Nevertheless, it has now accumulated so much material again that it would have enough for an atom bomb within a few months if it were to break all restrictions.
The "technical agreement" ends on Sunday
The heaviest weight is Iran's exit from the intensive controls of its nuclear activities agreed in the JCPOA.
Thanks to a special agreement between IAEA boss Rafael Grossi and the Iranian leadership, provisional further surveillance was achieved in February.
This “technical agreement” was limited to three months and ends on Sunday.
Senior diplomats in the E3 group reiterated the importance of Iran allowing the IAEA to continue its surveillance and verification work on Wednesday. "We urge Iran to find a way with the IAEA that ensures continuity of knowledge (about the nuclear program; ed.)." This is "essential" to restore the JCPOA. "A deal cannot be reached without this." Nevertheless, according to the Europeans, the technical agreement is only a makeshift. It is in everyone's interest that Iran apply again in full the additional protocol to the non-proliferation treaty suspended in February.
The US administration under President Joe Biden, in office since January, is ready to return to the JCPOA, but is demanding that Tehran comply fully with its regulations.
Iran is demanding a full lifting of all sanctions that have been imposed since 2018.
However, as Washington understands, some sanctions do not relate to the nuclear program, but to terrorist activities, for example.
Americans are meeting in another hotel
On the other hand, it must be negotiated what should happen to the technology that Iran has now set up, as well as to the stocks of enriched material.
The Iranian leadership has decided that their negotiators should not sit at the same table with the Americans until a return to the JCPOA is achieved.
The American delegation is therefore sitting in Vienna in a different hotel than the one where the negotiations are taking place.
It is obvious that this “proxy” format makes the conversations complicated and time-consuming, especially since the Americans also have to consult their government in Washington regularly.
However, no change is to be expected.