A fire at a Russian military research institute in the northwestern city of Tver killed five people Thursday and injured dozens more, state news agencies reported.

Russian TV showed images of thick black smoke rising from inside the yellow four-storey building of the Central Research Institute of the Russian Air and Space Forces. 

Several of the institute's employees had to jump out of windows on the upper floors to escape the flames, according to witnesses quoted by broadcasters.

"Twenty six people were injured in the fire, five of them died," a representative of emergency services told the RIA Novosti news agency. 

Several of the injured were taken to hospital, three of them requiring intensive care, said a spokesman for the Tver regional hospital, quoted by the TASS state news agency.

Preliminary information suggests the fire was caused by faulty electric wiring, TASS added. 

The defence ministry said the institute focuses on research related to Russian air and space defence, as well as the development of new anti-aircraft systems. 

Accidental fires are common in Russia, where hundreds of blazes are recorded each year due to ageing and dilapidated infrastructure and non-compliance with safety standards that are often lax.