It is not clear when work at the Isfahan conversion facility will be resumed. But an unnamed Iranian official privately told news agencies that IAEA technicians arrived at the facility today to install surveillance cameras.
The IAEA has said that its team needs until the middle of the week to get the inspection system in place before the facility could be restarted.
The moves to restart operations at Isfahan come as talks between Iran and three key EU states -- Britain, Germany and France -- over the Iran nuclear crisis have run aground, at least for now.
All activities at the Isfahan plant had been suspended since November 2004, following the agreement between Iran and the so-called EU-3 to engage in talks over the Iran nuclear crisis.
As a condition for the talks, Iran had promised to suspend all activities associated with uranium enrichment so long as the negotiations continued.
But on 6 August, Tehran formally rejected the European offer intended to solve the nuclear crisis. That offer was to give Tehran assistance with its commercial nuclear-energy program in exchange for Iran effectively abandoning efforts to produce its own nuclear fuel.
Western states fear that Iranian efforts to produce nuclear fuel -- including by uranium enrichment -- could help Tehran develop nuclear weapons.
Tehran’s decision to now restart the Isfahan plant -- first announced last week -- comes despite warnings from the EU that Tehran could be referred to the UN Security Council if it does so.
Iran's Foreign Ministry spokesman Hamid Reza Asefi on 7 August dismissed the European threat as politically motivated.
"I suggest that the Europeans avoid the language of threats," Asefi said. "The Europeans have called an emergency meeting for the IAEA...about Iran's nuclear case. We think the referral of Iran's case to the Security Council would be unlawful and politically motivated. If one day they refer Iran's case [to the UN Security Council], we won't be worried in the least. The Europeans should choose their way."
Asefi also said that the rejection of the EU offer by Iran does not mean -- for Tehran -- that negotiations will stop.
“We’d like to continue the negotiations because we think during talks both sides can get to know each other’s stances," he said. "But we don’t accept this offer and we will give EU our response.”
French Foreign Minister Philippe Douste-Blazy has urged Iran to go back and carefully consider the proposal. Douste-Blazy said in an interview published on 7 August that the EU package included an offer to make Iran a major oil-supply route between Central Asia and Europe.
As the crisis over Tehran’s controversial nuclear program escalates, the IAEA is due to meet on 9 August in Vienna at the Europeans’ request to discuss the issue.
It is expected that the UN nuclear watchdog will warn Tehran against resuming sensitive nuclear activities.
Meanwhile, Iran announced on 8 August that, based on a decision by the country’s new president Mahmud Ahmadinejad, former state broadcasting head Ali Larijani, a conservative with close ties to Supreme Leader Ayatollah Ali Khamenei, will soon replace Hassan Rohani as Iran's chief nuclear negotiator.
Rohani’s departure is considered a signal that Iran is set to further harden its stance in nuclear negotiations. During the presidential race, Ahmadinejad accused Iran's nuclear negotiators of being “frightened” during talks with EU representatives.
For RFE/RL's complete coverage of events in Iran, click here.