A video of the bus explosion in the central Russian city of Volgograd that killed six people and injured 27 has emerged online.

The footage emerged as authorities identified the female suicide bomber who led the attack as an Islam convert married to a high-level militant.

Dagestan-born Naida Asiyalova, 30, reportedly activated the bomb as soon as she got on the bus.

It is believed there were 40 people on board.

The Russian Investigative Committee said that the woman was "recently converted to Islam, and was the wife of a militant leader".

Seven passengers are in critical condition, according to reports, including a 20-month-old toddler.

Volgograd bus blast
Volgograd bus blast (RIA Novosti)