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Ukraine's security services on Tuesday said they had arrested pro-Moscow politician Viktor Medvedchuk, who is Russian President Vladimir Putin's closest and most influential ally in the country.
Ukrainian President Volodymyr Zelenskyy had earlier published a photo of a tired and handcuffed Mr Medvedchuk, who says Mr Putin is godfather to his daughter.
In February, Kyiv said the leader of the Opposition Platform – For Life party had escaped from house arrest.
Last year authorities opened a treason case against Mr Medvedchuk, who denies any wrongdoing.
"You can be a pro-Russian politician and work for the aggressor state for years," the security services said in an online post.
"You may have been hiding from justice lately. You can even wear a Ukrainian military uniform for camouflage.
"But will it help you escape punishment? Not at all. Shackles are waiting for you and the same goes for traitors to Ukraine like you."
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A boy rides a bicycle past a house that was damaged by shelling in Andriivka village, not far from Kyiv. EPA -
A destroyed residential building in Mariupol, south-eastern Ukraine. Reuters -
Firefighters at work on the outskirts of Kharkiv, north-east Ukraine. EPA -
A torn Ukrainian flag in front of a ruined Mariupol apartment building. Reuters -
Residents who cleared debris after Russian shelling eat lunch outside a damaged building in Makariv, near Kyiv. EPA -
Children play with a therapeutic dog at a shelter organised by volunteers in Zaporizhzhya, Ukraine. Reuters -
A girl stands by the door of a bunker in Severodonetsk, in eastern Ukraine's Donbas region, as Russian troops intensify a campaign to take the strategic port city of Mariupol. AFP -
A firefighter at work following a missile attack near Kharkiv International Airport. Reuters -
A Ukrainian fighter walks in front of a destroyed house in Bohdanivka village, north-east of Kyiv. AFP -
Two women hug outside a heavily damaged apartment block following an artillery attack in Kharkiv. Reuters -
Ukrainian soldiers guard the village of Barvinkove, as Russia's invasion on Ukraine continues. Reuters -
Leonid Serdiuchenko, a Ukrainian commander, stands next to destroyed vehicles outside Barvinkove. Reuters -
A woman carries the portrait of Dmytro Stefienko, 32, a civilian killed during the war, during his funeral in Bucha, Ukraine. AP -
A Russian soldier collects weapons from inside the Mariupol drama theatre in Ukraine. AFP -
Relatives and friends attend the funeral of Andriy Matviychuk, 37, who served as a territorial defence soldier, who was captured and killed by the Russian army in Bucha, Ukraine. AP -
Anatoliy Morykin, 45, left, mourns the death of his mother, Valentyna Morykina, 82, who died in a retirement home in Bucha during the Russian invasion. AP -
Nadiya, 65, shows a hole in a wall of a building after shelling in Zalissya, Ukraine. EPA -
A booby trap found by locals near their home in Zalissya. EPA -
Debris of a school bus near a damaged school that was a base for Russian troops in Bohdanivka, Ukraine. EPA -
A man examines the debris of a destroyed Russian tank in Bohdanivka. EPA -
President Joe Biden speaks to the media before boarding Air Force One at Des Moines International Airport, en route to Washington. AP -
Valentina Saroyan sits in the basement of a school in Yahidne, near Chernihiv, Ukraine. AP -
Vasyl Cherepenko stands next to a mass grave at a cemetery in Yahidne, near Dnipro, Ukraine. AP -
Oksana, second from left, and Yevhen, right, talk with police officers next to their apartment building damaged by shelling in Irpin, Ukraine. AP -
Women bid farewell to relatives as they leave the Slovyansk central station in the Donbas region. AFP -
The partially destroyed Mariupol drama theatre in Ukraine, hit on March 16 by an air strike. AFP -
A man embraces his wife as she prepares to board a train at Slovyansk central station in the Donbas region. AFP -
A woman walks through a damaged apartment building after a Russian attack in Kharkiv, Ukraine. AP -
A missile pierces the road in front of the Kharkiv Regional State Administration building amid Russia's attack on Ukraine. Reuters -
A boy walks by unexploded Russian shells in the village of Andriyivka close to Kyiv, Ukraine. AP -
Ukrainian tanks move down a street in Irpin, on the outskirts of Kyiv. AP -
A man walks past a storage place for burned armed vehicles and cars, on the outskirts of Kyiv. AP -
Local residents stand on top of a Russian tank on the outskirts of Kyiv. AP -
Ukrainian families, who have fled Kherson amid the Russian invasion, watch a dolphin show at a hotel in Odesa, Ukraine. Reuters -
Residents stand outside their apartments as shops burn after a Russian attack in Kharkiv, Ukraine. AP -
Irina Szymanska holds her baby in a temporary shelter at the central train station for displaced people heading to Poland in Lviv, Ukraine. Getty Images -
A man walks in his yard, damaged by shelling, in the village of Andriivka, Ukraine. EPA -
Sixty-two-year-old Luba hugs a Ukrainian servicewoman in Andriivka. EPA -
A woman washes clothes in the yard of a ruined house in Andriivka. EPA -
Russian soldiers patrol a street in Volnovakha, in the self-proclaimed Donetsk People's Republic. The picture was taken during a trip organised by the Russian military. AFP -
Russian mine clearers search for explosive objects in a building the Russian authorities say was damaged by Ukrainian shelling. AFP -
A woman reads a book as residents find shelter from shelling in a metro station in Kharkiv. Reuters -
Firefighters try to contain a fire at a plant in Kharkiv following Russian shelling. Reuters -
Farm owner Zlobina Lubov tends to her animals in the village of Malaya Rohan, Ukraine. Reuters -
A bathtub is seen inside a building that was heavily damaged by shelling in Kharkiv. Reuters -
A man looks out of his window, amid Russia's invasion of Ukraine, in Borodianka. Reuters -
Soldiers 'came to my house and said go to the basement' Zinaida Makishaiva, 82, said, before they started to shoot around her. 'God saved my life,' she said. Reuters -
A mother waits for police officers to exhume the body of her son from a well at a fuel station in Buzova, Kyiv region. According to the head of the village, he was killed by Russian soldiers. Reuters
The post quoted Ivan Bakanov, head of the secret services, as saying his operatives had "conducted a lightning-fast and dangerous multi-level special operation" to arrest Mr Medvedchuk.
Last month Mr Zelenskyy said the Opposition Platform – For Life, which is Ukraine's largest opposition movement, and other smaller political parties with ties to Russia had been suspended.
A spokesman for Mr Medvedchuk was not immediately available for comment.
