A comprehensive yoga programme for young students at a California school has sparked a religious controversy with some parents expressing concern that the exercises might nudge their children closer to ancient Hindu beliefs.

A small but vocal group of parents, spurred on by the head of a local conservative advocacy group, has likened these 30-minute yoga classes at Paul Ecke Central Elementary School to religious indoctrination.

Underlying the controversy is the source of the programme's financing. The pilot project is supported by the Jois Foundation, a nonprofit organisation founded in memory of Indian yoga teacher Krishna Pattabhi Jois, The New York Times reported.

Parents and the advocacy group say the classes — part of a comprehensive programme offered to all public school students in this affluent suburb north of San Diego — represent a violation of the First Amendment.

After the classes prompted discussion in local evangelical churches, parents said they were concerned that the exercises might nudge their children closer to ancient Hindu beliefs.

Opponents of the yoga classes have started an online petition to remove the course from the district's curriculum. They have shown up at school board meetings to denounce the programme.

Mary Eady, the parent of a first grader, said the classes were rooted in the deeply religious practice of Ashtanga yoga, in which physical actions are inextricable from the spiritual beliefs underlying them.

"They're not just teaching physical poses, they're teaching children how to think and how to make decisions," Eady was quoted as saying by the Times.

"They're teaching children how to meditate and how to look within for peace and for comfort. They're using this as a tool for many things beyond just stretching."