Police in Malaysia say a toddler has died after seven of her family members and a maid piled on top of her in a suspected exorcism.

The three-year-old girl's parents were among the adults who carried out the ritual late on Sunday in the town of Bukit Mertajam, a police chief said.

A local newspaper said the ritual lasted 20 hours, but police could not confirm the length of time.

The eight have been arrested, the local police chief Azman Abdul Lah said.

Police broke into the house after receiving a tip-off and found the eight piled on top of the toddler, he said.

The adults - including the girl's grandmother, uncle, aunt and two cousins - were in a dark room under a blanket, he added.

"They were chanting in the room. Police believe they were involved in an exorcism ritual to drive away evil spirits," he told reporters.

The girl died of suffocation, police said, and investigations were ongoing.