Talks got under way Saturday in Turkey between Iran and six world powers, as international diplomats seek to persuade Tehran to rein in its nuclear program.
Iran's top negotiator, Saeed Jalili, said ahead of the talks that he intended to bring "new initiatives" to the table.
He is meeting in Istanbul with delegates from the five permanent members of the United Nations Security Council -- the United States, France, Russia, China, and Britain -- and Germany, known as the P5+1.
That group has spearheaded diplomatic efforts to persuade Iran to rein in its nuclear program, which Iran has said is purely peaceful but which U.N. and Western leaders suspect of having military aims, including a possible nuclear weapon.
Jalili had dinner Friday night with EU foreign policy chief Catherine Ashton, who is leading the international negotiating team.
"What is gonna happen today is we hope that there will be some positive noises or proposals from the Iranian side that they want to engage in a serious substantive process of talks," said Michael Mann, a spokesman for Ashton. "If this round is successful we will be able to announce at the end of the day that there will be a second round."
As the negotiators broke for lunch, Mann said the mood appeared "more constructive and more positive than it was last year." There is "complete unity" from the side of the P5+1, he said.
Ashton said the atmosphere with Jalili was good, going into the talks, but that "much depends on what Iran is putting on the table today."
She added: "I hope what we will see today is the beginnings of a sustained process. What we are here to do is to find ways in which we can build confidence between us and ways in which we can demonstrate that Iran is moving away from a nuclear weapons program."
Iran last met with the six powers for talks on its nuclear program 15 months ago. That meeting, also in Istanbul, was widely regarded as ending in failure when Iran presented what the international side said were preconditions for talks.
Going into Saturday's meeting, the indications from behind the scenes were that both sides want to make progress.
Iran's Foreign Minister Ali Akbar Salehi said in an opinion piece published Friday in the Washington Post that Tehran that it is committed to a peaceful program, but it needs to see trust from the international side.
"Despite sanctions, threats of war, assassinations of several of our scientists and other forms of terrorism, we have chosen to remain committed to dialogue," he wrote.
"In the upcoming talks, we hope that all sides will return to the negotiating table as equals with mutual respect; that all sides will be committed to comprehensive, long-term dialogue aimed at resolving all parties' outstanding concerns; and, most important, that all sides make genuine efforts to reestablish confidence and trust."
However, Iran's official Press TV cited a source close to the Iranian delegation in reporting Friday that Iran sees little encouraging coming from the remarks of European and U.S. officials ahead of the talks.
Iran has been under increasing pressure to accept international demands to restrict its nuclear program, including a series of increasingly harsh economic sanctions imposed by European nations and the United States.
Last month, Iranian officials signaled they were ready to engage with the International Atomic Energy Agency, the U.N. nuclear watchdog, over the issue.
The European Union said Monday that Iran had agreed to Saturday's talks in Istanbul.
Iran suggested last week that one proposal may be a reduction in the amount of uranium it enriches to 20%, but it was unclear Friday if such a proposal was still on the table.
While the enrichment isn't enough to create nuclear weapons, which require a uranium content of 90% or more, analysts and inspectors say it is step toward being able to create a nuclear weapon.
Last month, the IAEA noted what it called a sharp and troubling increase in Iran's uranium enrichment capabilities.
Iran says the enrichment is for research and medical needs.
As a signatory to the Nuclear Nonproliferation Treaty, Iran has the right, like other countries, to enrich uranium for commercial and research reactors. But the same facilities that are used for peaceful enrichment can be used to enrich uranium for a bomb, and inspectors say they have not been able to fully gauge Iran's intentions.