Paris - On the eve of international talks in Baghdad over Iran's disputed nuclear program, the leader of the United Nations nuclear monitoring arm announced what appeared to be a significant concession from Tehran, saying that, despite unspecified differences, he expected a deal "quite soon" on arrangements for an investigation into potential military applications of the program.
The comments by Yukiya Amano, the director general of the International Atomic Energy Agency, came after his first visit to Iran since his appointment in 2009. Iran's invitation to Mr. Amano, announced unexpectedly on Friday, and the apparent shift by Tehran he announced on Tuesday, offered significant signals of Iranian flexibility.
The flurry of diplomacy reinforced the shift of focus to talks from the possibility of military action by Israel, but mixed messages from Iran — including sharp statements from political figures and a planned Wednesday satellite launch using a large missile — kept uncertainty high.
The I.A.E.A. and world powers are involved in separate talks with Iran: the nuclear agency is seeking access to Iran's Parchin military site, which the nuclear agency suspects has been used for secret tests for potential triggering mechanisms for nuclear weapons, while the Baghdad talks are to focus on limiting Iran's enrichment of uranium. For its part, Tehran is seeking reciprocal concessions like an easing of broad economic sanctions — including an embargo on oil deals starting July 1 and broad banking restrictions — at the Baghdad talks. In Iran's Parliament on Tuesday, the speaker, Ali Larijani, urged the global powers "to change their behavior and stop the shell game they have played on Iran," according to state-controlled Press TV. He also said it would be "improper" for the powers to adopt a cooperative stance during the Baghdad talks while imposing ever tighter sanctions.
Mr. Amano's report of progress, however, elicited a skeptical response from Israel and the United States. Israel considers Iran a threat to its existence and has threatened to bomb Iran's nuclear installations.
Ehud Barak, Israel's defense minister and a key architect of its hard-line policy on the Iranian nuclear program, said that Iran seemed to be trying to "create the impression of progress" to "remove some of the pressure" before the Baghdad talks and to "put off the intensification of sanctions."
"Israel believes that Iran should be set a clear bar, so that there is no window or crack" through which the Iranians could advance "their military nuclear program," Mr. Barak said during a meeting at the ministry of defense.
He reiterated Israel's position that Iran should not be allowed to enrich uranium at all and that all enriched uranium should be removed from the country, though he appeared to recognize the talks would not hold such a firm line. "Even if the Iranians are allowed to hold a symbolic amount — a few hundred kilograms of 3.5 percent enriched uranium — it needs to be under tight supervision," Mr. Barak said. But he also appeared to warn against compromise of any kind. "It is forbidden to make concessions to Iran," he said. "The requirements of the world powers must be clear and unequivocal."
Robert A. Wood, the chief American delegate to the nuclear agency in Vienna, said that while Mr. Amano's efforts were appreciated, the Obama administration remained "concerned by the urgent obligation for Iran to take concrete steps to cooperate fully with the verification efforts of the I.A.E.A., based on I.A.E.A. verification practices."
"We urge Iran to take this opportunity to resolve all outstanding concerns about the nature of its nuclear program," Mr. Wood said in a statement. "Full and transparent cooperation with the I.A.E.A. is the first logical step."
Mr. Amano spoke of the Iranian willingness to allow new access on his return to the nuclear agency's headquarters in Vienna on Tuesday. Speaking to reporters, he characterized the progress as an "important development" on the agency's push to reach what it calls a "structured agreement" to determine how its inspectors would conduct an investigation into possible military applications of the Iranian program.
"The decision was made to conclude and sign the agreement," Mr. Amano said, offering a vague timetable of "quite soon." Asked about the Parchin site, Mr. Amano said: "I have raised this issue of access to Parchin, and this issue will be addressed as a point of the implementation of the structured approach document."
"There remain some differences," he said, according to a transcript of his remarks released by I.A.E.A. officials, referring to his discussions with Saeed Jalili, Iran's top nuclear negotiator. But Mr. Jalili told him that existing differences "will not be the obstacle to reaching agreement," Mr. Amano said.
Mr. Jalili is scheduled to fly to Baghdad for the talks on Wednesday with Britain, China, France, Germany, Russia and the United States. There, negotiators will try to agree on the framework of the beginning of a compromise in which Iran would stop enriching uranium to 20 percent purity — a level considered a short technical step away from weapons grade. In exchange, world powers would allow the Islamic republic to produce its own fuel at a much lower rate of purity not usable for nuclear weapons.
Israel's skepticism of Iran's intentions mirror suspicions within the Tehran elite about outsiders' motives.
Hossein Shariatmadari, an influential adviser to Iran's supreme leader, Ayatollah Ali Khamenei, contended in remarks published Sunday that the purpose of Mr. Amano's sudden trip had been to frustrate Iran's negotiators by canceling a strategic meeting that was to have taken place in Vienna on Monday.
Those negotiators had been scheduled to receive long-awaited documents from the agency suggesting that the country had tested nuclear triggers in a blast chamber at Parchin. Iranian officials say they need the documents to prepare for the meeting on Wednesday with the world powers.
But other Iranian officials said Mr. Amano's visit was commendable.
"Visiting Tehran, for the first time, helps Mr. Amano to get a realistic impression of our nuclear activities," said Hamid Reza Taraghi, a political analyst close to Iran's highest leaders. "We need to continue this positive atmosphere in Baghdad."
On Monday, Mr. Netanyahu went out of his way on Monday to restate his hawkish position.
"The objectives of Iran are clear: It wants to destroy Israel and is developing nuclear weapons to realize that goal," Mr. Netanyahu said. The big powers "need to put before Iran clear and unequivocal demands: Iran must end all enrichment of nuclear material, Iran must remove from its territory all material that has been enriched up until now, and Iran must dismantle the underground nuclear facility in Qum."
Mr. Netanyahu's remarks came on a day that Haaretz, the left-leaning Israeli daily newspaper, published a front-page article suggesting that his administration "may be more flexible about Iranian low-level uranium enrichment than it is currently willing to let on." The article referred to a written statement by Mr. Barak, saying that enrichment up to 3.5 percent could be acceptable, and said Mr. Barak had shared this view with American officials.
A senior official with Netanyahu's administration denied the Haaretz report. Mr. Netanyahu himself said Israel's position "hasn't changed, and it won't change."
Earlier Monday, an Israeli vice prime minister, Moshe Yaalon, said that if the international community allowed Iran to maintain a civilian nuclear program, Iran would have successfully sacrificed "a pawn in a chess game in order to protect the king."
Over the years, a number of "breakthroughs" have collapsed, with skeptics arguing that Iran was simply buying time. In late 2007, the atomic agency cut a sweeping deal with Tehran to come clean on a number of contentious issues, most important being what the agency called "alleged studies" of atomic weaponization.
By early 2008, the so-called "work plan" had unraveled. Mohammed ElBaradei, the agency's director general at the time, recalled his aggravation at Iran avoiding what he described as a confession.
"It was undeniably frustrating," he wrote in a recent book. "I continued to press both sides, but no one was budging."
Alan Cowell reported from Paris; Thomas Erdbrink from Tehran; Jodi Rudoren from Jerusalem; and William J. Broad from New York.