Former king Norodom Sihanouk left for medical treatment in Beijing on Thursday on advice from his Chinese doctors, royal officials said.
He traveled with his wife and their son, King Norodom Sihamoni, and it was unclear how long they intend to stay.
In an October speech, the king said he had come back to Cambodia to stay, but a royal adviser said his medical condition had made it impossible to keep that promise.
Last week, the former monarch, a once powerful and revered figure to most Cambodians, issued an order that his body be cremated after his death.
Norodom Sihanouk, who is 90, has suffered from cancer, diabetes and hypertension and has made frequently, prolonged trips to China since abdicating the throne in 2004.
In a Jan. 6 missive, the former king said the “ashes of my bones to be clean and kept in an urn inside the Royal Palace.”
However, Chea Kean, vice president of the National and International Ceremony Organizing Committee, said he has no preparations yet for a state funeral or other ceremony.
Non Ngeth, head of the Nahanikaya branch of Cambodian Buddhism, said any preparation for a person’s death would be a way of looking down on his life.