Kiev, 7 May 2023 (dpa/MIA) - Ukraine's Air Force claimed to have shot down a Russian hypersonic Kinzhal missile on Saturday, which if true would be not only a military success, but also an important symbolic one.

"I congratulate the Ukrainian people on a historic event," Ukrainian Air Force Chief Mykola Oleshchuk wrote on his Telegram channel.

The Kinzhal, repeatedly touted by Moscow as one of the best missiles ever, was intercepted over the Kiev region on Thursday night with the help of the US Patriot air defence system.

There had already been speculation in Ukraine about a possible Kinzhal strike after military bloggers published photos showing debris from the missile.

The information could not be independently verified and the Russian side also did not react.

The 8-metre-long missile, the name of which translates as dagger, is particularly feared because it can fly extremely high and fast, making it hard to intercept.

Russia launched its full-scale invasion of Ukraine on February 24, 2022, and currently occupies some 20% of Ukrainian territory, including Crimea, which Moscow seized in 2014.

But the Kremlin's efforts appear to be faltering, with power struggles emerging within the Russian military leadership.

The head of Russia's Wagner paramilitary force, Yevgeny Prigozhin, is planning to withdraw his fighters from the front in eastern Ukraine, according to a statement issued on Telegram.

He wants to accept an offer from Chechen leader Ramzan Kadyrov, Prigozhin's press service said.

Kadyrov earlier said that men from his Akhmat troop could take over the positions of the Wagner mercenaries in the heavily contested Ukrainian town Bakhmut.

Recently, Prigozhin publicly complained about ammunition shortages, and on Friday said he would withdraw his fighters for this reason.

He has since published a letter addressing Russia's Defence Minister Sergei Shoigu, asking him to issue an order to hand over the positions to Kadyrov's men.

The letter says the operation is supposed to be completed by Tuesday at midnight (2300 GMT) - at the close of the day Moscow marks its victory over Nazi Germany at the end of World War II with military parades.

Russia's army, fighting in Bakhmut alongside Wagner's troops in what have been extremely costly battles, did not comment on Prigozhin's threats and accusations.

The Russian Ministry of Defence also refrained from comment on the issue on Friday, saying without explicit reference to Prigozhin that Shoigu had ordered arms deliveries to the combat zone be kept under "special control."

Meanwhile, Kiev and Moscow completed a further prisoner exchange.

The Russian Defence Ministry said three Russian Air Force pilots were released "as a result of a difficult negotiation process," while Kiev said 45 soldiers had been released from Russian captivity in return.

A total of 42 men and three women who defended Mariupol until its fall last spring, the head of the Ukrainian presidential office, Andrii Yermak, said on Telegram.

The exchange differs from many in the past since the number of Russians and Ukrainians exchanged has usually been roughly equal.