The U.N.'s nuclear watchdog says the situation at the former Chernobyl nuclear power plant is deteriorating. The International Atomic Energy Agency says it lost contact with staff working under Russian guard at the site of the 1986 nuclear disaster after power was cut on Wednesday. Ukrainian officials say operators have been forced to use backup diesel generators to power cooling systems that are needed to prevent a radioactive release. The IAEA says 210 technical staff and guards have not been allowed to rotate off shift or rest since Russian forces seized Chernobyl two weeks ago. The IAEA also says it was no longer receiving remote data transmissions from safety monitoring systems at Chernobyl, as well as the Russian-occupied Zaporizhzhia nuclear plant. On Thursday, IAEA chief Rafael Grossi held talks in Turkey with foreign ministers of Ukraine and Russia, urging them to reach a deal on the safety and security of Ukraine's nuclear sites.

Rafael Grossi: “Perhaps the gravity of my tone has to do with the gravity of the situation, because it’s a very dire situation, and we need to move fast.”

Meanwhile, Ukrainian officials say Russian warplanes bombed a physics institute in the eastern city of Kharkiv which houses an experimental nuclear reactor.