A seven-year-old boy taken from his school by a family member in Perth may be in imminent danger, police say.

Phoenix White was taken from his school in Harrisdale by a man at about 9.40am on Wednesday.

The man was riding a red/black motorcycle, believed to be a Yamaha.

“Information obtained since that time suggests Phoenix may be in imminent danger,” police said on Wednesday afternoon.

Phoenix was last seen travelling on Tonkin Highway, near Hale Road.

He is described as fair skinned, about 140cm tall, with a stocky build and blonde hair.

He was wearing blue shorts, a navy blue polo shirt with green side panels, a navy blue jacket and black shoes.

Anyone with information should call police on 000.