Iran's new foreign minister will join nuclear talks with his US counterpart and five other world powers later this week, the latest sign that long-standing tensions with the West might be easing.
The talks will be the highest level contacts between the US and Iran in six years.
European Union foreign policy chief Catherine Ashton told reporters of the new round of talks after she met Iranian foreign minister Mohammad Javad Zarif at the United Nations on Monday, a day before the opening of the UN General Assembly. She said the nuclear talks would resume Thursday on the sidelines of the General Assembly and US officials said Secretary of State John Kerry would participate.
"We had a good and constructive discussion," Ashton said of her half-hour meeting with Zarif. "We didn't talk about the details of what we would do. The purpose of this meeting was to establish how we would go forward."
On Twitter, the US-educated Zarif called the meeting with Ashton "positive" and added: "Need new start under new circumstances."
The meeting would be the first between a US secretary of state and his Iranian counterpart since May 2007, when US Secretary of State Condoleezza Rice met with Iranian Foreign Minister Manoucher Mottaki in the Egyptian resort of Sharm el-Sheikh.
Ashton said she and Zarif had also agreed to meet with their teams again in Geneva in October. Zarif confirmed there will be another round of nuclear negotiations in October. A European diplomat, speaking on condition of anonymity because discussions have been private, said political directors of the six countries will also attend the October meeting, which he described as a negotiating session.
Iran's new president, Hasan Rouhani, is scheduled to address the General Assembly on Tuesday in his first appearance on the world stage since he was elected in June.
Rouhani is considered a relative moderate among his country's hard-line clerical leaders and he has raised hopes of a thaw in relations with the US with a series of comments and gestures that appear more conciliatory than his predecessor, Mahmoud Ahmadinejad.
Just hours after Rouhani departed Iran for New York on Monday, his government announced that it had freed 80 prisoners arrested in political crackdowns.
US-Iran relations have been frozen since Washington severed ties after the 1979 Islamic Revolution. The US and its allies have long demanded that Iran halt nuclear activities that they suspect are geared toward producing an atomic bomb. Iran has repeatedly insisted its nuclear activities are only for producing energy and medical research.
The UN Security Council has imposed four rounds of sanctions against Iran because of concerns it is seeking to develop nuclear weapons and its refusal to suspend uranium enrichment - a process that can be used to make fuel for both energy and nuclear weapons. The US and its Western allies have imposed even more punishing sanctions.
Iran is hoping to get relief at the so-called P5+1 nuclear talks from the punishing Western sanctions that have crippled its economy, particularly by slashing its vital oil exports and severely restricting its international banking transactions.
Ashton, the chief nuclear negotiator for the world powers, said she was struck by the "energy and determination" in Zarif's attitude toward the nuclear talks, which include Germany and the five permanent members of the UN Security Council - the US, Russia, China, Britain and France.
"I have worked, I think, very hard to find a way in which we can address this issue of great concern, and I will take every opportunity to try and do that - and I hope this will be one."
Following his meeting with Ashton, Zarif held a series of bilateral meetings with Western officials including his British counterpart William Hague, who welcomed Iran's recent change of tone as well as the release of political prisoners.
"There's a chance, I think, for improved relations with Iran," Hague told reporters after the meeting. "Because if the statements of President Rouhani and foreign minister Zarif really mean something, if they really mean what they are saying, then certainly there's a chance for us to improve relations and to work together across a whole range of subjects. But it will be important, as I have stressed before, for those statements to be matched by concrete steps and action."
The meeting on Thursday will be the first since P5+1 nuclear talks stalled after an April round in Almaty, Kazakhstan. Rouhani last month made a potentially important shift by designating the foreign ministry to lead nuclear talks with world powers instead of security officials.
State Department spokeswoman Jen Psaki said the US hopes the new Iranian government "will engage substantively with the international community to reach a diplomatic solution to Iran's nuclear program and to cooperate fully" with the International Atomic Energy Agency - the UN nuclear watchdog - in its investigation.
"We remain ready to work with Iran should the Rouhani administration choose to engage seriously," she said.