A Russian military jet crashed into a residential building in the Siberian city of Irkutsk on Sunday and the two pilots were killed, officials said, the second such fatal incident in six days involving a Sukhoi fighter plane.

In a post on Telegram, Irkutsk governor Igor Kobzev said the plane crashed into a two-storey house in the city. He published a video showing firefighters clambering over the wreckage and directing jets of water at the still smouldering rubble.

Officials said the plane was a Sukhoi Su-30 fighter on a test flight. Last Monday, a Sukhoi Su-34 crashed into an apartment block in the southern city of Yeysk, near Ukraine, and at least 15 people were killed.

Authorities said initial investigation of that disaster - in which the pilots ejected - pointed to a technical malfunction of the aircraft.

Videos of Sunday's incident, shared on social media, showed the plane dived almost vertically before crashing in a fireball, sending dense black smoke into the sky. Kobzev said 150 nearby homes were without electricity and work was under way to restore power.

Russia's state Investigative Committee said it had launched a criminal investigation into violations of air safety rules.

-Foreign sources