A major fire broke out Wednesday in Moscow at a building belonging to Russian missile manufacturer Almaz, the maker of air defence weapons including the S-300 missile system, officials said.

The fire at the company's design bureau had spread over an area measuring 800 square metres (8,500 square feet) and dozens of firefighters had been sent to the scene, a spokesman for the Emergency Ministry, Yevgeny Bobylev said.

State television pictures showed a huge cloud of grey smoke rising into the sky from the area affected in the north of Moscow. Its cause was not immediately clear.