Russia has hidden the scale of the death toll at a top secret missile research plant after it went up in flames.
Footage showed a huge blaze at the building on Thursday and a death toll of up to seven was declared.
But now it is claimed at least 25 died, believed to include some of Russia ’s leading missile scientists.
Two days after the fire, a search was still underway amid the rubble, it was reported.
At least five are in intensive care.
The huge blaze was at the secret Second Central Research Institute of the Ministry of Defence of the Russian Federation in Tver.
Some military scientists jumped from upper floors to escape the intense heat and flames.
Reports at the time told of “poisonous bluish-black smoke”.
The institute is central to the design of Iskander missiles, which have been unleashed in the war in Ukraine, as well as Russia’s S-400 missile defence system.
It is involved in other “secret projects”.
Respected local journalist Alexander Gamburg reported on SOTA Telegram channel that he had exclusively seen the list of the “perished”.
“As of 10pm on April 22 there were 25 people,” he said.
“Seven from from April 21, and 18 people were found and identified on April 22.
“The youngest one is a major, a man born in 1983. The oldest is 90 or 91, born in 1931.
“I don't know what he was doing at his workplace at the research institute at this age.
“Most of the perished are men. The numbers are not final. This is a big tragedy.”
State media reported the toll as five or seven.
Gamburg made clear he could not give further details because of Russian censorship and “not to compromise people important and dear to me”.
He said: “Criminal investigators are working at the scene until Sunday, after which they are due to announce the losses.”
A case has been opened into how the fire was allowed to happen at the key Russian defence facility.
The damage is seen as a blow to Vladimir Putin ’s missile modernisation programme.
One rescued military scientist said they were faced with toxic black smoke blowing through long corridors.
“My colleague was feeling worse than me, I was still conscious.
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“He was no longer on his feet. I told the fireman that he should be pulled out first, but the rescuer replied that he could not raise him to his feet and I needed to be saved.
“Unfortunately, the colleague could not be resuscitated, he died.
“I came to my senses only in the hospital, after my first injection.”
An emergency helicopter was deployed to drop water on the burning institute which is now gutted.
