Cambodia's King Norodom Sihanouk has abdicated, an announcement made by his son, Prince Norodom Ranariddh, said Senate President Chea Sim would be interim head of state, but added that he hoped his father would change his mind.
Cambodia's monarchy is not hereditary, and a special throne council is due to meet soon to discuss what happens next.
The King, 81, has abdicated before and threatened to quit again many times. Ill health and political rows may have triggered the latest crisis.