Russian presidential human rights envoy Ella Pamfilova said in a phone conversation with Nadia Savchenko's sister that Nadia feels fine, Nikolai Polozov, a lawyer for Savchenko, said on Sunday.

"Nadia Savchenko now feels fine, she is under permanent visual observation, her arterial pressure is being measures," Polozov said on Twitter.

There is currently no need to force Savchenko eat and drink, Polozov said, adding that a group of Ukrainian doctors has been formed to examine Savchenko. He added, however, that the date when they will be given access to Savchenko is not known.

Savchenko has been held in Russian custody since July 2014 after being kidnapped by Russia-backed separatists and illegally taken across the Ukrainian border.

Russian investigators claim Savchenko was at the base of the Aidar battalion near the village of Metalist in the Slovianoserbsk district of Luhansk region in eastern Ukraine on June 17, 2014, where she was conducting secret surveillance and correcting artillery fire targeting a checkpoint of militants from the self-proclaimed Luhansk People's Republic, as well as civilians sheltering there; among them were three journalists of Russia's VGTRK broadcaster. Two Russian reporters, namely Igor Kornelyuk and Anton Voloshin, were killed in the attack.

Savchenko denies all charges.

She has been held in custody in Russia since July 2014. Savchenko went on hunger strike in the Donetsk City Court on December 17, 2015 until the end of her trial.

On March 4, Savchenko's lawyer Mark Feygin said his client went on a 'dry' hunger strike, which means she will also refuse water as well as food, despite remonstrations from her defense team.