The Bolshoi Ballet's artistic director says he is "absolutely certain" he knows who is behind an acid attack that left him badly injured last month.

Sergei Filin told the BBC he would not name names until investigators are ready to make an announcement.

Speaking to the BBC's Steve Rosenberg, he also gave more details of his condition: "I think that there's a chance that I will be able to see my children again. I really want to believe that."