The UN nuclear watchdog has reported that data connections between its offices and the Zaporizhzhya nuclear plant now occupied by Russian forces in Ukraine have been restored, allowing the agency to monitor stores of uranium and plutonium at the besieged facility’s six reactors.

The data connection had been severed for nearly two weeks after Russian troop activities interrupted service on Vodafone, a cellular carrier on which the International Atomic Energy Agency relies for its safeguard transmissions, the IAEA said in an update.

IAEA Director General Rafael Grossi called the development “an important and positive step for the implementation of IAEA safeguards at Ukraine’s largest NPP.”

But he reiterated his demand to send inspectors to the plant in order to carry out further physical inspections — a demand that has been rejected by the Ukrainian side and only tepidly received by the Russian occupiers.

“Remote transmission of safeguards data is an important element of IAEA safeguards in Ukraine and elsewhere,” Grossi said. “However, it is not a substitute for the physical presence of IAEA inspectors at NPPs to verify nuclear material at regular intervals.“

The transfer of safeguards data from IAEA systems installed at the Zaporizhzhya plant was cut on May 30 and re-established on Monday, June 12. The images recorded by IAEA surveillance cameras during the cellular interruption will downloaded for review by Agency inspectors to confirm that continuity of knowledge has not been lost.

Among those things inspectors will be keen to assess is the state of some 30,000 kilograms of enriched uranium and 40,000 kilograms of plutonium that are stored at the site as byproducts of burning nuclear fuel.

Grossi stressed that only a visit by inspectors could provide the necessary physical inspection of nuclear materials at two of Zaporizhzhya’s reactors that were refueled in recent months. According to the IAEA, this safeguards process is required before these reactors can be restarted.

But Grossi has thus far failed to secure support for such a visit. The suggestion was most recently rejected by the Ukrainian state nuclear corporation Energoatom, which last week said an IAEA visit to the plant would “legitimize” the presence of Moscow’s forces there.

The plant was overrun by Russian force in a dramatic attack on March 4, raising fears of a nuclear catastrophe. Since then, a third of the southeastern Ukrainian Zaporizhzhya Oblast, where the plant is located, has fallen to Moscow’s troops.

While not outright denying a visit to the IAEA, Russia has nonetheless been coy about whether it would allow it. The plant is currently being run by Ukrainian technicians, though Ukraine’s nuclear regulator has said they are taking orders from officials from Rosatom, Russia’s state nuclear corporation.