Questions remained Thursday over the military plane crash that Russia said had killed dozens of captured Ukrainian soldiers ahead of a planned prisoner exchange.
The Russian defence and foreign ministries blamed Ukrainian forces for downing the IL-76 transport plane over the southern Belgorod region.
They said 65 captured Ukrainian soldiers had been on board, as well as their escorts and the crew.
Videos on social media on Wednesday showed a large plane in the western Belgorod region plummeting from the sky on its side before crashing in a fireball, in what the Kremlin called a "monstrous act".
While officials in Kyiv have not denied the Russian allegations outright, they have questioned key aspects of its narrative -- such as whether its servicemen were killed.
Ukraine's military intelligence said it had no "comprehensive information" detailing who was on the flight.
Kyiv has confirmed that an exchange had been scheduled for later Wednesday on the border between the two countries.
But the military intelligence unit said Moscow had not informed it in advance that the POWs would be transported by plane, as it had in the past.
In another carefully worded statement, Ukraine's army pointed to heightened Russian military activity in the Belgorod region, pledging to "continue" attacking Russian military targets -- again without specifically addressing Moscow's claims.
Local Ukrainian media initially cited defence sources saying that the Ukrainian army had downed the plane, and that it had been carrying missiles. That claim was quickly retracted.
President Volodymyr Zelensky neither confirmed nor denied Moscow's claims, saying only that Russia was "playing with the lives of Ukrainian prisoners" and calling for an international investigation.
On Thursday, Ukraine's SBU security service announced it had opened a criminal probe into the downing, specifically into "violations of the laws and customs of war".
"The SBU is currently taking a range of measures to clarify all the circumstances of the downing," it said.
And Ukraine's rights Ombudsman Dmytro Lubinets on Thursday called for the United Nations and the International Committee of the Red Cross to be allowed to inspect the crash site.
The UN Security Council is due to meet later Thursday to discuss Moscow's charges that Kyiv shot down the military transport plane.
The French presidency of the Council said in a statement that the meeting requested by Russia would take place on Thursday at 5:00 pm (2200 GMT).
Russian officials rolled out a series of statements presenting its side of the story on Wednesday.
But Moscow has been more circumspect over previous incidents.
It offered no comment for example when Kyiv claimed last week to have downed an A-50 Russian reconnaissance plane and damaged an Il-22 bomber over the Azov Sea.
In August, the plane carrying the leader of the Wagner mercenary group, Yevgeny Prigozhin, crashed on a flight from Moscow to Saint Petersburg.
Prigozhin died alongside his top aides in the incident, two months after they attempted to topple Russia's military leadership, angering President Vladimir Putin.
Putin said the plane had crashed because passengers had detonated a grenade on board, but Moscow provided no evidence.
When in July 2014, Malaysia Airlines flight MH17 was shot down over eastern Ukraine with all 298 people on board killed, the Kremlin proposed a variety of explanations -- sometimes contradictory.
In 2022, a Dutch court sentenced three men fighting among Kremlin-backed separatist forces to life in prison in absentia.
Separately, a Ukrainian security source told AFP Thursday that Kyiv's security services had orchestrated an overnight drone attack on an oil refinery in the southern Russian town of Tuapse.
Kyiv has ramped up strikes on Russian oil and gas facilities over the past two months, part of what it has called "fair" retaliation for Russian strikes on its own energy infrastructure.
Ukraine has claimed responsibility for a string of attacks on Russian energy infrastructure in the past two weeks, including a huge inferno at a depot in western Russia last Friday.
