A four-year-old boy has died during an exorcism ritual carried out by a traditional healer in the Far East of Russia, investigators say.

The boy's mother went to police on Saturday after the boy died while visiting a "healer" in a village, investigators said in a statement on Tuesday.

"According to the boy's relatives, his death was caused by alternative medicine methods used on him," it said.

The boy along with family members visited an ethnic Korean healer in the village of Sergeyevka in the Far Eastern Primorye region, Komsomolskaya Pravda reported, citing relatives.

The healer said that the family had a curse on it because the boy was a "demon" and told them to leave while she carried out an exorcism, Komsomolskaya Pravda reported. When they returned, they found the boy had died.