Russian forces occupying the Zaporizhzhia nuclear power plant have turned the site into a military base to launch attacks against Ukrainian positions, the head of Ukraine's nuclear power company says.
Petro Kotin told the BBC the threat to the plant was "great", but that it remained safe.
For days, Ukraine and Russia have blamed each other for attacks on the site, Europe's largest nuclear plant, raising concerns of a major accident.
The complex has been under Russian occupation since early March, although Ukrainian technicians still operate it.
Over the weekend, Ukraine accused Russian forces of attacking the Soviet-era site, saying two workers were taken to hospital with shrapnel injuries and that three radiation sensors had been damaged.
Mr Kotin, who heads Enerhoatom, said 500 Russian soldiers were at the plant, and that they had positioned rocket launchers in the area, claims that cannot be independently verified.
"They [Russian forces] use it [the power plant] like a shield against the Ukrainian forces, because nobody from Ukraine is going to do something," Mr Kotin said.
"The Ukrainian Armed Forces know that these are Ukrainian personnel and this is a Ukrainian plant and there are Ukrainian people [there] so we aren't going to kill our people, our staff and damage our infrastructure."
The plant's staff, Mr Kotin said, were working under pressure and in danger, and some had been captured, beaten and tortured.
He said Russia's plans were to disconnect the plant from Ukraine's grid and eventually connect it to Russia's system.
Oleksandr Sayuk, the mayor of Nikopol, which sits on the opposite side of the Dnipro river, told the BBC last week that his city was under Russian shelling "almost every night", and that the attacks were being carried out by forces at the nuclear plant.
The tensions have led to growing calls for international inspectors to be allowed to visit the site.
The UN Secretary General, Antonio Guterres, said "any attack [on] a nuclear plant is a suicidal thing", while Ukrainian President Volodymyr Zelensky described Russia's actions as "nuclear terrorism".
"There is no such nation in the world that could feel safe when a terrorist state fires at a nuclear plant," Mr Zelensky said in his nightly address on Sunday.
Russia, however, denied the accusations, and blamed the Ukrainian forces for the attacks. The country's defence ministry said a high-voltage power line had been damaged as a result of the shelling.
The Institute for the Study of War, a Washington-based think-tank, said last week that Russia was using the plant to play on Western fears of a nuclear disaster, "likely in an effort to degrade Western will to provide military support" to Ukraine.