Slumdog Millionaire, the runaway hit film that has charmed audiences around the world, seems to have hit a sour note with one Indian activist a day before its release in India.

Tapeshwar Vishwakarma, representing a slum-dwellers' welfare group, is suing the film's music composer A R Rahman and one of its stars, actor Anil Kapoor, for depicting slum-dwellers in a bad light and violating their human rights.

Vishwakarma objected to the use of words such as "slumdogs" to describe the millions of inhabitants of India's cramped shantytowns, and filed a defamation case against the duo in the east Indian city of Patna, according to media reports Thursday.