"This is not a premeditated murder, but this does not lessen the gravity of the crime."
Medvedev ordered nationwide mourning for the victims on December 7, and demanded that legislators draft changes to strengthen the punishments for failing to comply with fire safety standards.
Fireworks to blame
The blaze was started by a fireworks display set off inside the club, where more than 200 people were partying early on Saturday, Russia's Itar-Tass news agency quoted police as saying.
Law enforcement officials ruled out the possibility that the blast was a "terrorist" act.
"The accident was due to a violation of instructions when launching fireworks," Russia's Interfax news agency quoted Vladimir Markin, a senior judicial official, as saying.
Al Jazeera's Neave Barker, reporting from Moscow, said dozens of victims who sustained burns in the fire are in critical condition and were sent to Moscow for specialist help.
"Medical teams and equipment have been flown into Perm to help the medical staff there - clearly overstretched by an incident of this magnitude," he said.
"An investigation has now begun and, according to local sources, the manager and owner of the club have been detained pending an inquiry.
"Officials have been cited as saying that the incident may have been caused by pyrotechnics that caused an explosion leading to a significant loss of life."
Russian state-run television channel Vesti-24 showed charred bodies piled on top of each other in the snow-covered street outside the club, where firemen and investigators cleared debris and recovered bodies.
The blast follows a deadly train bombing last week, which killed 26 and injured over 100 on a luxury train travelling between Moscow and St Petersburg, for which Chechen armed groups claimed responsibility.