VIENNA (AP) — A new and seemingly promising UN probe of allegations that Iran worked on atomic arms has stalled, diplomats say, leaving investigators not much further than where they started a decade ago and dampening US hopes of reaching an overarching nuclear deal with Tehran by a November deadline.

Expectations were high just two weeks ago, when chief UN nuclear inspector Yukiya Amano emerged from talks in Tehran with Iranian President Hassan Rouhani saying Iran had given “a firm commitment” of cooperation.

“We have started and that is important,” Amano said, suggesting that the years of deadlock had been broken.

His high-profile trip was meant to kick-start the latest effort to investigate the allegations. The investigation was agreed to in February but had made little progress.

Two diplomats told The Associated Press that Amano’s International Atomic Energy Agency will report no substantial progress this week, when it issues its latest confidential report on the status of the investigations — a finding that could impact on the Iran-six power nuclear talks.

IAEA spokeswoman Gill Tudor said Wednesday the agency would have no comment. Iran’s mission to the IAEA said Reza Najafi, the chief delegate to the agency, was in Tehran and nobody else could talk to reporters.

The IAEA inquiry is formally separate from those U.S.-led talks. But Washington says that a final deal must include a conclusion by the IAEA that it has satisfactorily completed its investigation.

With the IAEA still making little headway in getting answers on a dossier of allegations that extends to more than 1,000 pages, it is unlikely to be able to make that ruling by the Nov. 24 deadline, even if the two sides agree by then on the rest of a deal meant to limit Iran’s nuclear capacities in exchange for sanctions relief.

The Iran-six power talks already have been extended from a July 31 deadline due to wide differences between the two sides.

Iran’s reported refusal to advance the probe is bound to embarrass Amano considering his optimistic comments after his August 17 talks with Rouhani. It also will strengthen those in US Congress and elsewhere skeptical of predictions that Rouhani’s assumption of the presidency last year marked a full turn away from confrontation on the nuclear issue.

Iran and the IAEA agreed in February to a new start to the probe after a decade of deadlock, marked by Tehran’s insistence that the allegations were based on falsified intelligence from the United States and arch-foe Israel.

Since then, the UN agency has sought information on three issues: alleged experiments with detonators that can be used to set off a nuclear explosion; separate work on high-explosive charges also used in nuclear blasts, and alleged studies on calculating nuclear explosive yields.

The allegations are part of 11 suspected weapons-related experiments first outlined by the IAEA in 2011.

But Iran denies wanting — or ever working on — nuclear arms, and the diplomats said that as of Tuesday evening it had only provided information on the detonators, insisting that they were used only for oil exploration.

While such applications are possible, the agency says that its body of interconnected information suggests that they were being tested for nuclear weapons use.

No information has been given on the other two issues, the diplomats said, although two senior IAEA experts pressed Iranian counterparts for seven hours on the weekend during a visit to Tehran.

The diplomats — who are familiar with the issue but demanded anonymity because they were not authorized to discuss the confidential talks — said Iranian officials repeated familiar arguments, saying the allegations were untrue. They also dismissed IAEA requests to interview those suspected of involvement in the alleged experiments, saying that could expose the scientists to assassination attempts by Israel.

They say the agency recently suggested expanding the probe by two to four new topics but has not yet received an answer.

Copyright 2014 The Associated Press.