THE Klitschko brothers have reportedly both been put on a Russian "kill list" of senior Ukrainians the Kremlin wants dead amid Vladimir Putin's invasion.

Hundreds of highly-trained mercenaries, including the deadly private militia the Wagner Group, have been sent to Kyiv to assassinate Ukraine’s President Zelenskyy and decapitate his government.

Former boxing world heavyweight champions Wladimir and Vitali Klitschko have taken up arms to defend their country against Russia’s onslaught.

Vitali, the mayor of Ukraine’s capital, Kyiv, told Good Morning Britain he "will be fighting" after Russia declared war on its neighbour, and said his people were ready to "defend our city".

Last week, Wladimir issued a desperate video plea to other countries to help halt the invasion.

The Times reports that more than 400 Russian mercenaries are operating in Kyiv, with orders from the Kremlin to assassinate President Volodymyr Zelenskyy and prepare the ground for a new pro-Russian puppet government.

A private militia run by one of Putin's closest allies, the Wagner Group, flew in a number of mercenaries from Africa over a month ago, on a mission to take out Ukraine's government in return for a fee.

Kyiv found out about the plot on Saturday, hours before the city government declared a 36-hour "hard" curfew to sweep the city for Russian agents.

Civilians were warned they risked being "liquidated" if they stepped outside as they would be seen as Kremlin saboteurs.

A source claims between 2,000 and 4,000 mercenaries arrived in Ukraine in January, with many deployed to the disputed regions of Donetsk and Luhansk, whose independence Putin recognised last week, sparking conflict.

The mercenaries have reportedly been told to hold off while Putin shows the world he is negotiating with Zelenskyy, but when talks fail, they are to begin their mission, according to a source close to the Wagner Group.

They have also been preparing the ground for an invasion by helping to guide Russian columns to Kyiv as well as planning assassinations to destroy Ukraine's government.

Wagner is a private military company with close links to the Kremlin. It is owned by Russian oligarch Yevgeny Prigozhin, known as Putin's chef.

They have a previous history of covert operations on behalf of the Russian state across Africa and the Middle East and were also used during Russia's last military incursion into Ukraine in 2014.

The UN claims the Wagner Group committed war crimes in the Central African Republic, including killing kids, raping and torturing women, and executing men in mosques.

Mercenaries were alleged to have executed three young men inside the Al-Taqwa mosque in the town of Bambari as part of a savage attack in February 2021.

The group's links to Putin go back years, and Russia's president has been pictured at Kremlin functions with Wagner troops, including lieutenant colonel Dmitry Utkin, who is believed to have founded the group.

In 2020, investigative news site Bellingcat uncovered that Wagner's alleged boss Progozhin made 99 calls to Putin’s chief of staff in eight months and regularly spoke with top Kremlin officials.

But Moscow has insisted it has no influence over Wagner and says Prigozhin only provides the Russian government with catering services.

Sir Richard Barrons, former commander of Joint Forces Command, told The Times: "They are very effective because they are hard to pin down.

"They can appear from the shadows, do very violent things and then disappear again, without it being obvious who was responsible. They are not directly linked to the Russian government and therefore they are plausibly deniable."

Some claim the Wagner Group were briefed about a Ukrainian invasion as far back as December, long before the regular Russian army were told.