The blast tore through the Lame Horse nightclub in the centre of Perm, a city of 1.2 million near the Ural mountains, at 11:15 p.m. (2015 GMT).
“The latest death toll is 94 with another 139 people injured,” a spokeswoman for the local Emergencies Ministry said by telephone.
Russian state-run television channel Vesti-24 showed charred bodies piled on top of each other outside the club, where firefighters and investigators heaved debris and black body bags.
The blaze follows a train bombing last Friday which killed 26 and injured more than 100 on a train travelling between Moscow and St Petersburg, for which Chechen Islamist militants claimed responsibility.
That blast stoked fears that Russia could face a nationwide bombing campaign, but Russian officials played down any links between the train attack and yesterday’s nightclub disaster.
“We are not talking about a terrorist attack,” Oleg Chirkunov, the governor of Perm region, 1,150 km (720 miles) east of Moscow, told Vesti-24.
Detectives said they did not suspect a bomb attack.
“A firework blast sparked a blaze,” the Emergencies Ministry spokeswoman said.
Blood-covered women in evening clothes were shown lying on stretchers as scores of policemen swarmed around. At least 200 people were dining in the club.
Russian President Dmitry Medvedev ordered the formation of a government commission to deal with the incident.
Prime Minister Vladimir Putin sent Emergencies Minister Sergei Shoigu, Health Minister Tatyana Golikova and Interior Minister Rashid Nurgaliyev to the scene to coordinate rescue efforts.
