The European Union's foreign policy coordinator, Catherine Ashton, read a statement at a brief press conference in Geneva early on Sunday, announcing that no deal had been reached after the marathon negotiations.

"A lot of concrete progress has been made, but some differences remain," said Ashton, who is the chief negotiator representing the five permanent members of the United Nations Security Council plus Germany.

She also announced that negotiations would continue on November 20th.

"Our objective is to reach a conclusion and that's what we'll come back to try to do," Ashton said.

Iranian Foreign Minister Mohammad Javad Zarif, who appeared with Ashton at the joint press conference, described the negotiations as "a very productive three days. That's something we can build on."

Asked if he was disappointed that they had failed to reach at least a preliminary deal, Zarif stressed the positive.

"I'm not disappointed at all because the meeting we just had, very long, running after midnight, was a good meeting," he said. "We are working together and hopefully we will be able to reach an agreement when we meet again."

Rouhani weighs in

On Sunday, Iranian President Hassan Rouhani said his country would not abandon its nuclear rights, including uranium enrichment.

"There are red lines that must not be crossed," he told the Iranian parliament in remarks quoted by the ISNA news agency.

"The rights of the Iranian nation and our national interests are a red line," he added. "So are the nuclear rights under the framework of international regulations, which include enrichment on Iranian soil."

Possible agreement presumed

Just 24 hours earlier, though, some had suggested that some sort of agreement in Geneva could be imminent.

This speculation was supported by the fact that the foreign ministers of Germany, Britain and France had rushed to Geneva on Friday to join the talks involving Ashton and Zarif, as well as US Secretary of State John Kerry. It also came despite the fact that Kerry and others involved in the talks had warned that much work still needed to be done.

By Saturday, even the arrivals of Russian Foreign Minister Sergei Lavrov and China’s deputy foreign minister, Li Baodong, weren’t enough to maintain a similar level of optimism.

French Foreign Minister Laurent Fabius played down the possibility that a deal could be reached this weekend.

"As I speak to you, I cannot say there is any certainty that we can conclude," Fabius said in an interview with France Inter radio on Saturday, adding that Paris was determined not to settle for what he described as a "sucker's deal."

Germany’s foreign minister, Guido Westerwelle, noted that "there is still hard work to be done."

Israel's objections

While Kerry and the others were negotiating in Geneva, Israel, which was not a party to the talks, warned against any agreement with Iran.

On Friday, Israeli Prime Minister Benjamin Netanyahu accused Kerry of offering Tehran "the deal of the century." He added that Israel would not be bound by any agreement with Tehran. A White House spokesman played down the concerns, saying they were premature as no such agreement had yet been reached.

Iran has been at loggerheads with much of the international community for years over its nuclear program, which Israel, the US and at its allies fear it could be using to try to develop an atomic weapons capability.

The proposed agreement discussed over the past three days in Geneva is aimed at allaying Western concerns about Iran's nuclear ambitions in return for a relaxation of some crippling economic sanctions on Tehran.

pfd,dr/mr (Reuters, AFP, AP)