Russian authorities on Wednesday charged a captured Ukrainian military pilot with complicity in the deaths last month of two Russian journalists, spurring accusations in Kiev that the female officer was abducted by pro-Russia militants and illegally transferred to Russian custody.
A statement from the Russian Investigative Committee in Moscow said Nadezhda Savchenko, 31, was arrested after crossing the border into Russia disguised as a refugee, an account that Kiev authorities denounced as "absurd."
The committee, the Russian equivalent of the FBI, accused Savchenko of tipping off Ukrainian troops to the location of a reporter and soundman from Russia's state-run broadcaster RTR. The two men died in a June 17 airstrike against a roadblock manned by pro-Russia separatists.
Savchenko, a veteran of the international peacekeeping force in Iraq before attending a Ukrainian air force academy in 2009, was reportedly on leave from her military air unit and fighting with a pro-government volunteer militia when she was captured by separatists last month in the village of Shchastya, near Luhansk, Ukrainian and Russian media reported.
Ukrainian President Petro Poroshenko believes she was taken across the border by the militants and handed into Russian custody, National Security and Defense Council spokesman Andriy Lysenko told journalists in Kiev. The president has ordered judicial authorities to determine the circumstances of her arrival at a pretrial detention center in Voronezh, Russia.
Ukrainian Foreign Minister Pavlo Klimkin said a Ukrainian diplomat had been in Voronezh, about 300 miles from Luhansk, for the last two days in an unsuccessful effort to meet with Savchenko.
"We have every reason to suspect that she was brought to Russia as the result of an agreement or a joint operation between the terrorists and the Russian secret services," Foreign Ministry spokesman Yevhen Perebyinis said.
In a statement posted on the ministry's website, the government said the incident was further evidence of Kremlin involvement in the separatist insurgency, which has claimed about 500 lives since it began in the Donetsk and Luhansk regions in April.
"This is yet another proof that terrorists are planning and committing their crimes on the territory of Ukraine in close cooperation with the secret services of the Russian Federation," the Foreign Ministry said.
"By kidnapping Ukrainian citizens in our country, the Russian side violates not only all the norms of international law, but also the basic rules of decency and morality."
Perebyinis said the government had information that Savchenko was held by the militants in eastern Ukraine after her capture, adding that the report from the Russian Investigative Committee "that she was released from captivity and for some reason was trying to get into the Russian Federation is absurd."
Russia may want to use Savchenko as leverage with Poroshenko's government, since the Ukrainian military's recent success in recovering control of several separatist strongholds has emboldened Kiev to spurn Russian appeals for a new cease-fire.
Poroshenko proclaimed a unilateral halt to the fighting on June 20 to give the separatists a chance to lay down their arms in exchange for amnesty. Kiev authorities say the cease-fire was violated by the militants more than 100 times before the president declined to extend it after 10 days.
Russian Foreign Minister Sergei Lavrov said during a meeting with his Italian counterpart in Rome on Wednesday that the pro-Russia separatists were ready to negotiate and should not be thwarted by "ultimatums and pre-conditions," an apparent reference to Poroshenko's insistence that the militants first disarm if they want peace talks.
There were fresh indications Wednesday from Donetsk that the separatists, who have been regrouping in the regional capital since losing Slovyansk, Kramatorsk and other key cities to the government in recent days, are having trouble maintaining control of the territory they have seized.
Pavel Gubarev, self-proclaimed governor of the so-called People's Republic of Donetsk, said at a news conference that Russian forces had refrained from intervening on behalf of the separatists because of pressure from oligarchs fearful of the effect the fighting could have on their investments amid sanctions imposed by the United States and the European Union.
Gubarev alluded to infighting in the separatist ranks, acknowledging that the Donetsk-based commander no longer controlled the Vostok Battalion, holder of key checkpoints in the region, the Associated Press reported from Donetsk.
In another sign of the separatists' eroding appeal in Russian-speaking eastern Ukraine, their military commander, veteran Russian special forces officer Igor Strelkov, was reportedly offering, via radio appeals, to pay volunteers about $430 to $690 a month to come to the rebels' aid in the looming battle for Donetsk, the Reuters news agency reported.
Donetsk is the industrial heart of eastern Ukraine and was a city of a million residents before it became the focal point of the fighting.
Follow @cjwilliamslat for the latest international news 24/7