Russia says no threat after blast in lab holding smallpox

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.

The blast happened Monday at "Vector", a state-run virus and biotechnology research centre 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.

Glass was broken but the structure of the building remained intact and there were no biohazardous materials in the room where the explosion happened, the watchdog said.

The fire was extinguished Monday, authorities told news agencies.

The blast near Novosibirsk, the country's third most populous city, is the latest to hit Russian state facilities this year.

In August, one person died and thousands had to be evacuated because of a fire at a Siberian ammunition depot that set off a series of dramatic explosions.

Later the same month, an explosion at a missile testing site in the far north killed five nuclear agency staff and caused a spike in radiation.

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