Nikolai Tsiskaridze, one of the Bolshoi's best known male principals through his extensive television work, was questioned on Wednesday, police said in a statement.

"Employees of the Bolshoi Theatre and relatives and acquaintances of Filin have also been questioned," said the statement quoted by Russian news agencies.

Tsiskaridze is the first figure to be named by police as a witness in the case.

The Bolshoi's management and Filin himself have blamed last week's attack on internal divisions within the company although they have not publicly pointed any fingers at individuals.

Tsiskaridze, a flamboyant figure with flowing black hair who regularly appears as a judge on TV talent shows, last year lashed out at the Bolshoi's leadership for not giving him enough lead roles.

The Izvestia daily said Tsiskaridze had aroused the attention of investigators with his repeated criticism of the Bolshoi management.

He has not been named as a suspect, and on Wednesday he vehemently denied any link to the attack.

"What happened (to Filin) is horrific," Tsiskaridze told the RIA Novosti news agency while complaining of "systematic persecution" by the Bolshoi.

Filin is currently undergoing a series of operations in a Moscow hospital to save his eyesight and repair the disfigurement he suffered when an unknown individual threw acid in his face.