Ukraine's Defense Ministry was in deep turmoil over a corruption scandal as the country sent mixed messages about the fate of its defense minister on Monday.

The crisis leaves a key post in its war effort in doubt even as it braces for a new Russian offensive.

The questions left dangling over Defense Minister Oleksii Reznikov were the first public sign of serious disarray in Ukraine's wartime leadership, until now remarkably united during almost a year of all-out Russian military assault.

A day after announcing that Reznikov would be sidelined, a top ally of President Volodymyr Zelenskiy appeared to row back for now, saying no personnel changes in the defense sector would be made this week.

David Arakhamia, chief of the parliamentary bloc of Zelenskiy's party, had said the head of military intelligence, Kyrylo Budanov, would take over the defense ministry, while Reznikov would be made minister of strategic industries.

But Zelenskiy remained silent on the issue, while Reznikov said on Sunday he had not been informed of any move and would reject the strategic industry job if offered it.

The confusion caps a two-week crackdown on alleged official wrongdoing in Ukraine that has led to the biggest shakeup since Russia's invasion.

Central and regional officials were fired or quit, security forces raided a billionaire's home and investigations were launched into suspected fraud at the main oil company and refinery. The Defence Ministry was caught up in accusations it contracted to overpay for food, although Reznikov was not personally accused of any wrongdoing.

Zelenskiy says the actions are intended to show that Kyiv can be a safe steward of billions of dollars of Western aid. But they risk destabilizing the political class that had stood together against Russia's invasion.

Meanwhile, Russian forces have been advancing for the first time in six months in relentless battles in the east. A regional governor said Moscow was pouring in reinforcements for a new offensive that could come as soon as next week.

'Everything will be resolved'

Reznikov, a 56-year-old lawyer, has been the face of Ukraine at international meetings when allies have pledged billions of dollars in arms and has been warmly received in Western capitals including Paris just last week.

One obstacle to replacing him with Budanov, an enigmatic, fast-rising 37-year-old military intelligence officer decorated for operations that remain secret, is a rule requiring the defense minister be a civilian.

Volodymyr Fesenko, a political analyst at the Penta think tank, said he expected Budanov to request retirement from the military before his appointment, while Reznikov could be given a post of the special envoy, making use of his stature abroad.

"Everything will be resolved," Fesenko told Reuters.

Ukraine's defense ministry did not respond to a request for comment regarding Reznikov and Reuters could not immediately reach Reznikov or Budanov directly.

In announcing plans for the change, Arakhamia said Ukraine's armed forces should be overseen by people with a background in defense or security in wartime: "War dictates changes in personnel policy," he wrote on the Telegram messaging app.

But Zelenskiy adviser Mykhailo Podolyak noted that Reznikov was respected by allies: "Reznikov was extremely efficient in terms of communication with our partners. And this is a very important component in this case."

Reznikov said on Sunday any decision on a reshuffle was up to Zelenskiy but the planned transfer was news to him. He would reject the strategic industry job if offered it, because he lacked the expertise, he was cited as saying by Fakty ICTV online media.

Offensive at any time

The war is reaching a pivotal point as its first anniversary approaches, with Ukraine no longer making gains as it did in the second half of 2022 and Russia now pushing forward with hundreds of thousands of mobilized reserve troops.

Ukraine is planning its own counter-offensive, but waiting on promised Western battle tanks and infantry fighting vehicles.

Russia was sending more reserves and equipment into eastern Ukraine, Serhiy Haidai, governor of the eastern Luhansk region said on television, adding that shelling was no longer round-the-clock as Russian forces prepare for a full-scale offensive.

"After Feb 15 we can expect (this offensive) at any time," he said.

Russia's Defense Ministry said its forces had taken control of Mykolaivka, a small village in the adjoining Donetsk region, according to state media. There was no immediate response from Ukraine, which has disputed other Russian battlefield reports.

Russia's main target has been the town of Bakhmut, where its state media said the Wagner mercenary group had gained a foothold.

A Belarusian volunteer fighting for Ukraine inside Bakhmut said earlier that Ukrainian forces were still in control of the town, although more Russian forces were appearing daily.

"Reinforcements are also arriving for us. As far as I know, the intention isn't to surrender Bakhmut," he said.

Wagner chief Yevgeniy Prigozhin, accused by Ukraine of sending thousands of Russian ex-prisoners to their deaths around Bakhmut, released a video saying he was in a tactical bomber plane that had just bombed the town. He said he would fly a fighter jet on Tuesday and challenged Zelenskiy to an aerial duel.