Zelensky's decision to remove Reznikov comes after several corruption scandals rocked the defence ministry, and the Ukrainian leader removed senior military recruitment officials across the country.

"I have submitted my letter of resignation to Ruslan Stefanchuk, Speaker of the Parliament of Ukraine," Reznikov said on social media.

"It was an honour to serve the Ukrainian people and work for the (Ukrainian army) for the last 22 months, the toughest period of Ukraine's modern history," he added.

Ukraine launched a counter-offensive against Russian forces in June after building up Western-supplied weapons, a drive to which Reznikov was seen as being central. Progress has been limited.

Zelensky nominated Rustem Umerov, a Crimean Tatar who has been head of the State Property Fund since last year, to replace Reznikov -- subject to approval by Ukraine's parliament.