A pro-Kremlin official in the Russian-controlled port city of Berdyansk in southern Ukraine was in a serious condition Tuesday after being injured in a car blast, Moscow-installed authorities said.

City commandant Artem Bardin was taken to hospital "in a serious condition" after the explosion of a bomb in his car, local officials in the city said.

Earlier, his death had been announced by the Berdyansk city authority and a pro-Kremlin regional official later retracted that to say Bardin was alive but seriously hurt.

"He is seriously injured but fortunately alive. The doctors are battling to save him," said the head of the Moscow-installed Zaporizhzhia region administration, Yevgeny Balitsky.

Local pro-Russian officials have accused "Ukrainian terrorists" of being behind the attack, which they said aimed at intimidating Ukrainian officials who had sided with the Russians.

In recent months, several officials installed by Russian forces in Moscow-controlled territories in Ukraine have been killed or wounded in attacks.

Kyiv has not formally claimed responsibility for them.

In late August, Alexei Kovalev, a former lawmaker who switched allegiance and became a senior official in the Russian-installed administration, was shot dead.

Ukraine has claimed its first gains in a counter-offensive against the Russian army in the south, saying it has recaptured several areas and destroyed multiple targets.

Russian-installed authorities in the occupied Ukrainian region of Kherson on Monday hinted at delays in southern Ukraine referendum plans amid the counter-offensive.