Jailed Ukrainian pilot Nadiya Savchenko went on trial in Russia Thursday in a politically charged case that could send ties between Moscow and Kiev to a new low.

The 34-year-old helicopter navigator faces up to 25 years in prison for her alleged involvement in the killing of two Russian journalists in eastern Ukraine last year.

Savchenko, who is seen by her compatriots as a symbol of resistance against what most Ukrainians consider an insurgency fuelled by President Vladimir Putin's government, has denied any involvement.

She has been in detention for more than a year and was Thursday put in the dock in the small southern Russian town of Donetsk on the border with war-torn eastern Ukraine.

Her lawyers say the choice of the location is aimed at shielding the proceedings from the public eye.

The trial started with a closed preliminary hearing at the Donetsk city court, with a heavy police presence in the border town of some 50,000 people.

Embassy staff from Britain, the United States, Canada, Norway, Austria and the EU arrived in Donetsk but were not allowed to attend the opening of the trial.

The defence team said they had finally seen Savchenko and she was doing fine.

"She is okay," lawyer Mark Feigin said on Twitter.

Her lawyers -- including Feigin who said he took a flak jacket with him to Donetsk -- said they would ask the court to move the trial to Moscow and away from a town close to a conflict zone.

Donetsk has no jail and Savchenko has to be transported to hearings from Novocherkassk, a city located nearly two hours away by car.

Few doubt that the Ukrainian pilot's fate will really be decided in the Kremlin, and Western leaders and Petro Poroshenko of Ukraine have repeatedly called on Putin to let her go.

-'100 percent alibi'-

Two journalists from Russian public broadcaster VGTRK, Igor Kornelyuk and Anton Voloshin, died from shelling on June 17, 2014, in Ukraine's Lugansk region.

Russian prosecutors accuse Savchenko of her involvement in the killing of the journalists in her capacity as a volunteer in a Ukrainian battalion.

The prosecution also accuses her of illegally crossing the border into Russia on June 23, 2014, where she was detained.

Savchenko has denied the claims and refused food for more than 80 days to protest her detention. She broke off her hunger strike in March because of severe health problems.

Her defence argues that data from phone bills data confirmed that Savchenko had already been taken prisoner by separatists when the Russian journalists died, insisting she was taken to Russia against her will.

"Savchenko has a 100 percent alibi," said Ilya Novikov, another of her lawyers.

Russian justice denied Savchenko a trial by jury, which statistically is more likely to deliver a not guilty verdict.

Moscow is prosecuting Savchenko despite diplomatic immunity she enjoys as a lawmaker and a member of the Ukrainian delegation to the Parliamentary Assembly of the Council of Europe.

Kiev accuses Russia of effectively kidnapping and smuggling her across the border, and Ukraine's General Prosecutor's office on Wednesday announced it suspected six Russian officials of taking part in her detention and prosecution.

-'Harshest possible sentence'-

Novikov said Russian officials are likely to rush through the trial to further complicate matters for the defence and dismiss expert conclusions that he said prove her innocence.

"This is a political case pursued by Russia, and in Russia political cases are predictable," he said.

"We'll be working on the assumption that the sentence has already been written and it's the harshest possible."

Savchenko is one of the first Ukrainian women to train as an air force pilot and served in Iraq for six months.

In an interview with a Ukrainian newspaper in 2009, she said she could go without sleep for five days and had no problem sharing a room at night "with 25 guys."

This month another prominent Ukrainian, film director Oleg Sentsov, went on trial in Rostov-on-Don on terror charges in a case decried by Kiev.

Kiev and the West accuse Russia of buttressing separatists and sending weapons and troops across the border in a conflict that has claimed at least 6,800 lives since April 2014.