The Chernobyl nuclear power plant’s systems stopped transmitting data to the United Nation’s atomic watchdog on Tuesday, Agence France-Presse reported.

International Atomic Energy Agency chief Rafael Grossi said that contact was lost with the Chernobyl nuclear power plant in northern Ukraine “without warning”.

“I am deeply concerned about the difficult and stressful situation facing staff at the Chernobyl nuclear power plant and the potential risks this entails for nuclear safety,” said Grossi, Agence France-Presse reported.

It was estimated that more than 200 technical staff members and guards were trapped inside the facility since Russia invaded Ukraine on February 24.

Russian President Vladimir Putin has described the invasion as a “special military operation” aimed at dislodging the “neo-Nazis” ruling Ukraine.

The Russian forces on February 25 seized the defunct Chernobyl nuclear power plant, where a disaster in 1986 killed hundreds and spread radioactive contamination to many parts of Europe. The staff continues to work at the site to prevent another nuclear disaster.

Grossi said that the situation of the staff “was worsening” at the site. He called on Russia to allow workers to take rest on rotation as it was crucial to the site’s safety.

Grossi even offered to travel to the site to ensure “the safety and security” of Ukraine’s power plants from all parties. The remote data transmission was cut off since the invasion and so the Ukrainian regulator is only able to communicate with the plant through email.

Meanwhile, the International Atomic Energy Agency said that it was scrutinising the status of safeguards monitoring systems in other nuclear sites in Ukraine.

The agency’s “safeguards” include technical measures that it applies to nuclear material and activities. Its aim is to curb the spread of nuclear weapons by detecting misuse of such material at the earliest.

Last week, Russia also attacked and seized Zaporizhzhia, Europe’s largest atomic power plant. The power plant – Europe’s largest – had caught fire following Russian strikes. The radiation levels of the plant have remained unaffected.