The Kremlin on Monday declined to comment on reports it had sacked the commander-in-chief of its navy after losing a string of warships to Ukrainian attacks in the Black Sea.

Several news outlets including the pro-Kremlin Izvestia newspaper said over the weekend that Admiral Nikolai Yevmenov had been replaced by Northern Fleet commander Alexander Moiseyev.

The Kremlin refused to comment on the reported appointment, which would typically be announced by presidential decree.

"There are decrees labelled secret, I cannot comment on them. There were no public decrees on this matter," Kremlin spokesman Dmitry Peskov told reporters.

Yevmenov, 61, was appointed head of the navy in May 2019.

If confirmed, his removal would be the biggest shakeup in Russia's military top brass since the sacking of aerospace force chief Sergei Surovikin last year.

Ukrainian forces claim to have destroyed more than two dozen Russian ships since the conflict began in February 2022, including a military patrol boat last week.

The sinkings are an embarrassment for Moscow, which has been forced to move boats from its historic Sevastopol naval base in Crimea to the port of Novorossiysk, further east.

Russia's Black Sea woes come in stark contrast to its land offensive in east Ukraine, where its forces have advanced in recent months after over a year of deadlocked fighting.