Russian troops are approaching a second nuclear power plant in Ukraine, after capturing Chernobyl.
Ukraine's interior ministry has said the invading troops are approaching Zaporizhzhia.
Vadym Denysenko, an adviser in the Ukraine government, said Russian troops have aimed their rockets at the site.
Kremlin troops stormed the site of the Chernobyl nuclear disaster on the first day of the invasion.
Since then excess gamma radiation levels have been recorded but it is unclear why.
The State Inspectorate for Nuclear Regulation of Ukraine (SINR) said the exact reasons for increasing radiation in the seized city were unknown.
But Russian officials have denied the allegations that there has been any increase in levels and said it would deploy paratroopers to guard the Chernobyl nuclear reactor.
Norway's nuclear monitoring agency weighed into the argument claiming it is concerned by "elevated" levels of radiation, but added that they do not pose a "threat to health" in the area at present.
The Norwegian Directorate for Radiation Protection and Nuclear Safety released a statement saying they were in contact with Ukrainian authorities who had raised concerns.
In a statement, it said: "They have raised questions about whether the increased values are due to heavy vehicles that have whirled up radioactive pollution from the Chernobyl incident in 1986."
The area has been largely uninhabited since the devastating explosion of a nuclear reactor in the town of Pripyat in April 1986 which left toxic levels of radiation across the land.
But the Ukrainian SINR claims that data from the automated radiation monitoring system of the exclusion zone, shows excessive levels of gamma radiation at a number of observation points.
A spokesman for Russia's defence ministry refuted these claims, adding that troops were being deployed to stand guard of the closed power plant.
"Radiation levels at the plant are normal" he told a briefing on Friday.
