The sister of an imprisoned Ukrainian pilot on trial in Russia says her sibling will go on hunger strike unless she is extradited back home after the verdict.

Closing arguments in the trial of Ukrainian pilot Nadezhda Savchenko begin on Wednesday with the verdict expected to follow shortly.

Savchenko, who then fought in a volunteer battalion, was captured by Russia-backed rebels in eastern Ukraine in June 2014 and accused of involvement in the deaths of two Russian journalists who were killed in an artillery strike.

The Ukrainian government was counting on the high-profile prisoner to be exchanged for Russians held in Ukraine.

Savchenko's sister Vera said in an interview this week that Nadezhda has pledged to go on hunger strike unless she is sent back home.