Russia on Thursday accused the United States of secretly producing and testing biological weapons including anthrax and plague in ex-Soviet Georgia in violation of international legislation.
The Russian defence ministry's claims came as Western powers accused Moscow of orchestrating a string of global cyber attacks including an audacious plot to hack the world's chemical weapons watchdog in The Netherlands.
Igor Kirillov, commander of Russia's radiation, chemical and biological protection troops, said the clandestine US laboratory was run out of the Lugar Center near the Georgian capital Tbilisi.
"It is highly likely that the United States is conducting its activities in contravention of international agreements and continuing to ramp up its biological warfare potential," he told a briefing attended by foreign attachés.
The US-funded centre was established in 2011 but this year a new eight-storey building was erected nearby, he said.
Two floors in the new building are occupied by US ground troops and the laboratory deals with patients "infected by agents of especially dangerous diseases," Kirillov claimed.
Georgian employees have no access to the laboratory, while US military biologists enjoy diplomatic immunity, he said.
Kirillov's statement was based on materials provided by Igor Giorgadze, a former state security minister in Georgia.
"Among the priorities of US research are potential biological warfare agents: tularaemia, anthrax, Mediterranean fever, dengue, Crimean-Congo haemorrhagic fever and other diseases that are spread by bloodsucking insects," said the senior military official.
He added that the United States is especially interested in atypical forms of plague and is guided by the principle "the more atypical, the better."
The Georgian health ministry denied the claims as "absurd."
"We have repeatedly said that nothing of this kind happens in this center," a representative said.
Moscow has long accused the United States of running a network of labs close to Russia's borders.