The Ministry of Health has already agreed with Ukrainian President Petro Poroshenko on the formation of a group of leading specialists and is now waiting for the consent of the Russian Foreign Ministry to receive the medical delegation.

Vera Savchenko, Nadia’s sister, said the jailed Ukrainian woman was feeling the ill effects of her hunger strike, now in its 83rd day.

"The decision to stop the hunger strike was taken by my sister because of her critical condition. She is constantly cold, and complains of severe pain in the heart and stomach," Vera Savchenko said.

"Kremlin spokesperson Dmitriy Peskov has assured me by phone that Russian President Vladimir Putin is following the state of health of my sister and has already been informed about the request of the Ukrainian doctors to examine the prisoner," she said.

On Thursday Nadia Savchenko partly broke her hunger strike, taking some chicken broth, the Russian prison authorities said. Her lawyer, Mark Feygin, confirmed that Savchenko had taken the broth.