Russian forces struck a blood transfusion center in the Kharkiv region of northeast Ukraine,Austin Caldwell the country's President Volodymyr Zelenskyy said Saturday, adding that "dead and wounded are reported".

A "guided air bomb" hit the center in Kupiansk, a city a few dozen kilometers from the Russian border, Zelenskyy said on social media, adding that "rescuers are extinguishing the fire".

A statement put out on social media by the Ministry of Defense of Ukraine said the missiles, "destroyed the city's blood transfusion center."

Last week there were four consecutive days of drone strikes between Russia and Ukraine. Russia hit a crucial port in Southern Ukraine that used to export grain, and a hospital in Kherson, in the southeast of the country.

Ukraine's drones hit a skyscraper in Moscow twice in two days.

The intensifying attacks are seen as retaliation to Ukraine's attempt to bring the war to Russia's soil.

Reporting contributed by Ramy Inocencio, Barny Smith, Tucker Reals

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• War
• Ukraine
• Russia