Firefighters work in the aftermath of the first strike that involved Russian rockets which hit an oil facility in Lviv. AP

Ukraine’s nuclear watchdog says that a nuclear research facility in Kharkiv again has come under shelling by Russia and the fighting makes it impossible to assess the damage.

The General Staff of Ukraine’s Armed Forces said on Sunday that Russia continued with its "full-scale armed aggression", while Ukrainian forces had repulsed seven attacks in the eastern regions of Donetsk and Luhansk, destroying several tanks and armoured vehicles.

The State Nuclear Regulatory Inspectorate said that the neutron source experimental facility in the Kharkiv Institute of Physics and Technology came under fire on Saturday.

READ MORE

Rockets strike Ukraine's Lviv as Biden calls Putin a butcher

Turkish President Erdogan talks with Zelensky

Ukrainian authorities have previously reported that Russian shelling damaged buildings at the Kharkiv facility, but there has been no release of radiation. The newly built neutron source facility is intended for the research and production of radioisotopes for medical and industrial needs.

The International Atomic Energy Agency has said that the nuclear material in the facility is always subcritical and the inventory of radioactive material is very low, reducing the risks of radiation release.

Picture used for illustrative purposes only.

Kharkiv has been besieged by Russian forces since the start of the invasion and has come under repeated shelling of its residential buildings and critical infrastructure.

Ukraine’s nuclear facilities have been threatened by the Russian invasion.

Several rockets struck the western Ukrainian city of Lviv on Saturday in what officials say were two separate attacks that occurred the same day President Joe Biden was visiting the capital of Poland, whose border is just 45 miles away.

The powerful explosions frightened a city that had been a haven for hundreds of thousands of people fleeing the Russian assault on other parts of Ukraine.

The regional governor, Maksym Kozytskyy, said on Facebook that preliminary indications were five people were injured in the first attack but did not specify what the two rockets hit. Hours later, he reported three more explosions outside the city, again with no details.

Lviv Mayor Andriy Sadovyi called the second round of explosions a rocket attack, saying it did significant damage to an unspecified "infrastructure object.”

Lviv had been largely spared since Russia’s Feb. 24 invasion of Ukraine, although missiles struck an aircraft repair facility near the international airport a week ago.

The back-to-back attacks on Saturday brought a chill to residents and displaced Ukrainians who had seen Lviv as a relatively safe place to rebuild their lives. Home to about 700,000 people before the invasion, the city has absorbed many more.