Zelenskyy said he fired a top security official for 'thinking only of himself' instead of defending his city as Russia invaded

• Zelenskyy said Sunday that he fired the head of Ukraine's Security Service in Kharkiv.
• Zelenskyy said the SBU official was "thinking only of himself" and "not working to defend the city."

President Volodymyr Zelenskyy said he fired a top Ukrainian Security Service (SBU) official for "thinking only of himself" as Russian forces tried to seize Kharkiv.

Speaking in his Sunday address, Zelenskyy did not give details of what exactly the official did to warrant dismissal.

He also did not name the man, but Ukrainian media have identified him as Roman Dudin, the head of the SBU in Kharkiv.

Zelenskyy said the official was fired "for not working to defend the city from the first days of a full-scale war."

"What were the motives? Law enforcement officers will find out."

Separately, in early April, Zelenskyy said he had fired two other SBU officials for being "traitors," identifying them Andriy Olehovych Naumov, chief of the main department of the SBU, and Serhiy Oleksandrovych Kryvoruchko, the head of the SBU in Kherson.

Zelenskyy's statement on Sunday came hours after he had visited Kharkiv, a city which Ukraine fought hard to save, forcing back an intense Russian assault.

Russian forces are still firing missiles at the city from positions to the north.

"Kharkiv suffered terrible blows from the occupiers," Zelenskyy said.

"I held a meeting with the leadership of the region and the city. Thanked them for being and remaining together with the people of Kharkiv."

In recent weeks, Russia has focussed its efforts on controlling the Donbas region of eastern Ukraine, which has been run by pro-Kremlin separatists since 2014.

Zelenskyy said that Russia is making it "very complicated" for Ukraine to reclaim ground in the region, and other Ukrainian officials have admitted that they are conceding ground to the Russian advance.

Russian foreign minister Sergei Lavrov said Sunday that taking the Donbas was an "unconditional priority" for Russia.