A group of Russian bloggers claimed to have gained access to the Roscosmos agency's Energomash plant in Moscow's Khimki district, which manufactures liquid-propellant engines for civilian and military rockets, RIA Novosti reported Thursday.
The bloggers claim they were able to wander freely about and take pictures for five days and did not see any security officers.
Deputy Prime Minister Dmitry Rogozin said harsh measures would be taken to enforce security and punish the "sleepy cats" responsible for maintaining security at the facility.
"There will be no freewheeling," Rogozin told Roscosmos chief Vladimir Popovkin.
He issued a warning to the bloggers, calling them "cheeky mice."
"I don't advise anybody to penetrate strategic installations anymore," he said.