A Russian court has rejected an appeal to release a Ukrainian military officer who has been on hunger strike since mid-December in a Russian prison.
The case of 33-year-old Nadezhda Savchenko has attracted high attention in recent weeks as concerns rise about her health.
In addition to Ukraine, both the United States and the 28-nation European Union have demanded that Russia release the woman who is seen as a national hero in Ukraine and has been elected to parliament.
Ms Savchenko has been in Russian custody since June on charges that she provided guidance for a mortar attack that killed two Russian journalists who were covering the war between Ukrainian troops and Russia-backed separatists in eastern Ukraine. At the time of the attack, she was on leave from the military and working as a spotter with the Aidar volunteer brigade in eastern Ukraine.
The circumstances of her capture remain unclear. Russia's Investigative Committee alleges Ms Savchenko crossed into Russia voluntarily and illegally, disguised as a refugee. But Ms Savchenko says she was captured by the separatists in eastern Ukraine and spirited across the border into Russia.
Ms Savchenko is widely lauded at home. She was well known even before her captivity because of her stint as a soldier in Iraq with a Ukrainian contingent and later as one of the nation's few female military pilots.
Last autumn she was elected a member of the Ukrainian parliament and appointed a delegate to the Parliamentary Assembly of the Council of Europe (Pace), an arm of the continent's leading human rights body. The rejected appeal asked for her to be released in order to attend a Pace session.
On Tuesday, Pace president Anne Brasseur said "time is running out" to save Ms Savchenko's life but the state of her health is under debate.
Russian officials have said she is not in immediate danger and if there is a serious change in her condition, she would be sent to a civilian hospital. In her court appearance on Wednesday, Ms Savchenko, wearing a red-and-white jumper, appeared glum but not disabled.
In an interview with the Open Russia website this month, Ms Savchenko said she has been consuming a compound that includes protein and lactose.
"I am taking this mixture so that my brain will be the last thing to break down. Only for this," she said.
Ms Savchenko's case has been a contentious issue in the Ukrainian conflict and in Russia-West relations. Ukraine demands that she be considered a prisoner of war, which would nominally make her eligible for the prisoner exchange taking place in stops and starts under a stumbling internationally brokered peace agreement.
On Monday, the presidents of Ukraine, France and Germany appealed to Russian president Vladimir Putin to release Ms Savchenko. Ukrainian president Petro Poroshenko said he had written separately to Mr Putin. But the Kremlin has not responded publicly yet.
Russia has insisted that Ms Savchenko must face trial. Keeping her in custody has also given Russia leverage to repeatedly denounce Ukrainian forces as the killers of journalists.