President Volodymyr Zelenskiy dismissed Ukraine's Air Force Commander Mykola Oleshchuk on Friday, according to a presidential decree.

The dismissal was announced just a day after the Ukrainian military reported that an F-16 jet crashed and its pilot died while repelling a major Russian strike on Monday.

"I have decided to replace the commander of the Air Forces... I am eternally grateful to all our military pilots," President Volodymyr Zelenskiy said in his evening address.

He did not give a reason for dismissal but mentioned that personnel must be protected, and that there was a need to strengthen the command level.

Ukraine's General Staff said that General Lieutenant Anatoliy Kryvonozhka would temporarily perform the duties of commander.

The Ukrainian military did not provide a reason for Monday's crash but said the jet came down while it was approaching a Russian target. Oleshchuk said on Monday partners from the US were helping to investigate the incident.

A US defence official said that the crash did not appear to be the result of Russian fire, and possible causes from pilot error to mechanical failure were still being investigated. (Reuters)