G7 Ambassadors said Thursday they were deeply concerned about Ukrainian filmmaker Oleg Sentsov, who has been on hunger strike for more than a month as he serves a 20-year term in a Russian prison camp.
"We are deeply concerned about the situation of Oleg Sentsov and other Ukrainian prisoners and detainees in Russia," the countries' ambassadors to Kiev said in a joint statement released via Twitter.
"Their release, as part of a broader bilateral exchange of detainees, would be an important humanitarian step forward," it said.
The US Embassy in Kiev urged Russia to act as the eyes of the international community are on the World Cup host country.
"With the world watching the World Cup, Russia should allow access to all Ukrainian prisoners, including film director Oleg Sentsov, who is in his 2nd month of a hunger strike in a Russian prison," the embassy tweeted.
On Thursday Ukrainian President Petro Poroshenko spoke with his Russian counterpart Vladimir Putin via telephone, the leaders' second call in the past month.
Poroshenko again urged the Kremlin to free Ukrainian political prisoners and underlined the importance of allowing Kiev's rights ombudsman access to all of them, but especially to hunger-striking Sentsov.
The Kremlin said that during the call, initiated by Kiev, the sides touched on the topic of prisoner exchange and visits by monitors from each country to the other's prisons.
The 41-year-old Sentsov has refused food since May 14, demanding Moscow release all Ukrainian political prisoners.
His lawyer Dmitry Dinze who visited Sentsov on Thursday told Russian media that the filmmaker had lost 13 kilograms, is drinking 3.5 litres of water a day and is currently in the Arctic prison's medical centre where he is receiving a drip.
He added that Sentsov is starting to experience problems with his heart and kidneys and that he was briefly taken to hospital on the 26th day of his hunger strike, when doctors wanted to force feed him but Sentsov refused food. According to Dinze, "this crisis can restart at any time."
Major figures from Russia and abroad have called for Sentsov's release, including Oscar-nominated director Andrei Zvyagintsev and US author Stephen King.
Sentsov, a pro-Ukrainian activist and documentary director, was detained in Crimea in 2014 after Russia annexed the peninsula on accusations of masterminding arson attacks.
He denied the allegations but was found guilty on terrorism charges and is serving a 20-year sentence in Russia's far north.