Six more women have stepped forward to accuse prominent conductor Charles Dutoit of sexually assaulting them in the United States, France and Canada, including a musician who says the maestro raped her in 1988.

The new accusers said they were angered by Dutoit's denial of an Associated Press report last month of four accusations of sexual assault and also wanted to show the scope of his inappropriate behaviour during his globe-trotting career.

They said the Swiss-born conductor attacked them in Paris, Montreal and the United States over a four-decade period, starting in the late 1970s.

Through his attorney, Dutoit issued a "categorical and complete denial' of the new accusations and said he was especially "appalled and sickened" that someone had accused him of rape.

Dutoit, who married Canadian violinist Chantal Juillet in 2010, was the artistic director of the Montreal Symphony Orchestra between 1977 and 2002.

He resigned amid complaints from the Quebec Musicians' Guild about "offensive behaviour and complete lack of respect for the musicians."