Russia has said there is no threat of contamination after an explosion and fire at a Soviet-era biological weapons facility in Siberia that stocked samples of the Ebola and smallpox viruses.

Axar.az reports citing Medicalexpress that the blast happened Monday at "Vector", a state-run virus and biotechnology research center that is one of only two locations in the world to hold the smallpox virus.

The Russian health watchdog Rospotrebnadzor said a fire broke out when a gas cylinder exploded, injuring one worker at the facility. The blast near Novosibirsk, the country's third most populous city, is the latest to hit Russian state facilities this year.

Russian authorities have refused to release details of the blast and President Vladimir Putin said there was "no threat" from radiation following the test.