Ukraine's parliament is calling on the leaders of Russia, Germany and France to make efforts to free Nadezhda Savchenko, a Ukrainian air force officer who is on hunger strike in a Russian prison.

Savchenko, awaiting trial on charges of involvement in the killing of two Russian journalists during the conflict in eastern Ukraine, began the second month of a hunger strike on Tuesday, her lawyer Mark Feygin said on Twitter.

After her imprisonment in Russia, Savchenko was elected to the Ukrainian parliament in October.

The resolution also calls on the Parliamentary Assembly of the Council of Europe to engage in efforts to free Savchenko.