Expectations were high just two weeks ago, when chief U.N. nuclear inspector Yukiya Amano emerged from talks in Tehran with Iranian President Hasan Rouhani saying Iran had given “a firm commitment” to cooperation and suggesting that years of deadlock had been broken.

Two diplomats told The Associated Press that Amano’s International Atomic Energy Agency will issue a confidential report this week saying that Iran has not provided information to substantially advance the probe, a finding that could affect talks between Iran and six major powers.

The diplomats spoke only on condition of anonymity because they are not authorized to discuss the confidential talks. IAEA spokeswoman Gill Tudor said Wednesday that 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.

On Friday, August 29, the US Department of State and the Treasury Department placed 25 Iranian individuals and entities in the sanctions list for their involvement in Iran’s missile and nuclear programs, sanctions evasion efforts, and support for terrorism.

The main entity placed under sanctions by the State Department was SPND, a body that functions as the brain center of Iranian clandestine nuclear weapons program. The principal Iranian opposition group, the People’s Mojahedin organization of Iran, MEK, exposed SPND in July 2011.

A determination that the IAEA probe has stalled would embarrass Amano considering his optimistic comments after Aug. 17 talks with Rouhani. It also would strengthen those in U.S. Congress and elsewhere who are skeptical of predictions that Rouhani’s assumption of the presidency last year marked a 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 1,000 pages of allegations of nuclear activity were based on falsified intelligence from the United States and arch-foe Israel.

Since then, the U.N. 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.

Iran denies wanting — or ever working on — nuclear arms. The diplomats said that as of Wednesday morning it had provided information only on the detonators, insisting that they were used 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 during a visit to Tehran this weekend.

The diplomats said Iranian officials dismissed IAEA requests to interview those suspected of involvement in the alleged experiments, saying that could expose the scientists to assassination attempts by Israel.