"In recent days, we have taken all the possible measures to put international pressure on Russia from the EU, US and our other partners, demanding the immediate and unconditional release of Nadiya Savchenko from jail and her return to Ukraine," Poroshenko said in a video statement posted on Facebook.
The pro-Western Ukrainian leader, who is currently visiting Turkey, called Savchenko's trial a "farce" that is being conducted in a "kangaroo court".
Savchenko is accused of involvement in the death of two Russian state television journalists in a mortar attack that occurred two months after revolt erupted in Ukraine's pro- Moscow east in April 2014.
Savchenko denies the charges and has refused all food and drink since her hearing was adjourned last Thursday before she was given a chance to make a final statement.
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Her hearing resumed today with the judge saying that the verdict will be handed down on March 21 and 22.
Speaking to the court Savchenko said she would continue refusing food and water in protest.
Ukrainian Prime Minister Arseniy Yatsenyuk today called Savchenko's trial "a challenge to the entire civilised world".
"The entire civilised world must -- not just in words but in action -- prove that in this world there are human rights and respect for the individual."
"That is why the entire world community must free Nadiya Savchenko," Yatsenyuk was quoted as saying on the government's website.