Il Nuovo Postiglione - Ukraine state energy boss Koretsky becomes new PM

Koretsky, 48, is seen by Zelensky as a manager who can lead the country through another tough winter set to be marked by relentless Russian strikes on the energy system.

But the Ukrainian leader has not fully explained the reasons for the shake-up of Ukraine's top political team, which triggered an outcry on Thursday over the ousting of the popular defence minister.

"We weathered the harshest winter and ensured an uninterrupted supply of gas to Ukrainians, despite significant losses of our own production," Koretsky said in a parliamentary speech, hailing his achievements as head of Naftogaz.

"We have proven that government administration can and should be effective," he added.

Koretsky led Naftogaz, the backbone of Ukraine's heating system, through last winter, when Russian drones and missiles sparked mass blackouts and heating outages during freezing temperatures.

Yulia Svyrydenko resigned as prime minister on Tuesday as part of the reshuffle, for which Zelensky offered only the vague explanation that Kyiv was "changing its political strategy" amid "new challenges and new tasks".

Early Thursday, protests erupted in several Ukrainian cities after news of the ousting of popular reformist defence minister Mykhailo Fedorov, with demonstrators demanding he be reinstated.

The reshuffle comes at a pivotal moment in the more than four-year war, with Russia escalating its deadly ballistic missile strikes on Ukraine, and Kyiv planning to produce US Patriot air-defence missiles domestically.

T.Barbieri--INP