Kupiansk, Ukraine - Moscow escalated its attacks in Ukraine on Saturday, with President Volodymyr Zelensky denouncing a deadly strike on a blood transfusion center as a "war crime."

A separate strike struck a key factory, both attacks coming just hours after Kyiv hit a Russian tanker in the Kerch Strait.

The attacks were the latest since Moscow exited a deal last month that had ensured Ukrainian grain exports despite the ongoing conflict.

Russian forces struck the blood transfusion center in the Kharkiv region of northeast Ukraine, Zelensky said, adding that "dead and wounded are reported."

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A "guided air bomb" hit the center in Kupiansk, a city a few dozen miles from the Russian border, said Zelensky.

"Rescuers are extinguishing the fire," he wrote on social media, adding: "This war crime alone says everything about Russian aggression."

The strike came shortly after Zelensky said Russian missiles had hit a facility of the Ukrainian aeronautics group Motor Sich, a maker of plane and helicopter engines and other components.

It is one of several companies requisitioned by the government since Moscow's invasion. The Motor Sich site is near Khmelnytskyi in western Ukraine, around 190 miles southwest of Kyiv.

The region, home to a major Ukrainian airbase, has been regularly targeted by Russian strikes in recent months.

In his evening address, Zelensky remained defiant, insisting that "no matter how many such Russian attacks there are, they will still do nothing for the enemy."