A man accused of sexually assaulting a seven-year-old girl at a Sydney dance studio will face an additional 87 charges when he appears in court on later Tuesday.

Anthony Peter Sampieri, 55, was charged in November with holding the young girl captive in the bathroom of a Kogarah dance studio where he allegedly abused her on November 15.

Documents filed to the court last year alleged he held the girl at knife point for half-an-hour before he locked her in a men’s toilet cubicle.

Sampieri allegedly stabbed a man who came to the girl’s rescue before a second man subdued him while police were called.

He will now face further charges after investigators identified and interviewed potential victims who reported they had received offensive and obscene phone calls, police said.

On Monday night, NSW Police said he was charged with 87 counts of using a carriage service to menace, harass or offend.

Detectives went to Silverwater Correctional Centre – where Mr Sampieri is being held – yesterday morning and charged him with 87 instances of using a carriage service to menace, harass or offend.

Sampieri remains in custody and will appear at Sutherland Local Court.

-with AAP