Russia said Wednesday the toll climbed in its worst single reported loss from a Ukrainian strike, which under-criticism Moscow blamed on troops using mobile phones.
The Ukrainian military's strategic communications unit has said nearly 400 Russian soldiers were killed in the town of Makiivka in eastern Ukraine, and even Russian commentators have said the death toll may be far higher than the 89 Russia has reported.
As Moscow grappled with the aftermath of the strike, France's President Emmanuel Macron told Ukrainian leader Volodymyr Zelensky that his country would send French-made light tanks to help repel the Russian invasion.
The death toll in Makiivka is the highest reported by the Russian military in a single strike since its troops invaded Ukraine in February 2022.
The deadly strike came after months of discontent towards the military, since the Kremlin suffered a series of battlefield defeats and launched a hugely unpopular mobilisation drive.
Russia's defence ministry initially said on Monday that 63 soldiers had been killed, in an extremely rare admission.
On Wednesday, the ministry said the toll had climbed to 89 after more bodies were found under the rubble of the temporary base where the troops were housed.
It announced a commission was working to clarify what happened and vowed that "guilty" officials would be punished.
In a video, Lieutenant General Sergei Sevryukov said the tragedy had likely taken place because Russian troops had used cell phones, giving away their location to Ukrainian forces.
But some critics have said the military is trying to shift the blame, and Russian military correspondents have accused commanders of incompetence.
The strike also led to rare public displays of grief, including in the Samara region on the Volga River where some of the victims were from.
Thousands of people have been killed in Ukraine and millions forced to flee their homes since President Vladimir Putin ordered troops to attack on February 24.
Following a wave of Russian strikes on Ukrainian targets on New Year's Eve, Moscow said Ukraine struck Makiivka at 12:01 am local time on January 1, using US-supplied HIMARS rocket systems.
Putin has not yet commented on the strike, which came shortly after his New Year address in which he hailed Moscow's "heroes" fighting in Ukraine.
- Western tanks -
The French presidency said Macron wanted to increase aid to Ukraine "by accepting to deliver AMX-10 RC light tanks."
"It is the first time that Western-designed tanks are supplied to the Ukrainian armed forces," the presidency said after both leaders spoke by telephone. No other details were provided.
Zelensky on Twitter said he thanked Macron "for the decision to transfer light tanks" to Ukraine.
In Russia, calls mounted to draw conclusions after the Makiivka tragedy.
The influential head of state television channel RT, Margarita Simonyan, welcomed the army's promise that officials "will be held accountable."
"I hope that the names of these persons" will be announced, she said.
"It is time to understand that impunity does not lead to social harmony. Impunity leads to new crimes. And, as a result, to public dissent."
There have been reports that the servicemen were quartered in an unprotected building which was destroyed because munitions were stored on the premises and detonated in the strike.
- 'Hero' troops praised -
Dmitry Azarov, the governor of the Samara region, was due to visit the wounded that had been brought to the southern city of Rostov near the Ukraine border.
In comments to local media, he hailed the "courage" of the troops.
"After the shelling soldiers and officers -- wounded and with concussions -- saved others, pulling comrades from under the rubble," Azarov said.
Among the dead were rank-and-file soldiers as well as "representatives of the command staff", he said.
East Ukrainian separatist leader Denis Pushilin also hailed the "heroism" of the troops.
"The majority of them, after barely getting out of the building hit by American Himars and regaining consciousness, returned back to pull out their comrades," Pushilin said on Telegram.
The Russian-installed head of the occupied part of the southern region of Zaporizhzhia, Yevgeny Balitsky, said five people were killed and another 15 wounded in the town of Vasilyevka.
On the Ukrainian side, the general staff reported Russian shelling in Kramatorsk, Zaporizhzhia and Kherson.
The presidency said five people had been killed and 13 wounded by Russian fire in the past 24 hours.