Chinese activist Chen Guangcheng has left the US embassy and is being taken to join his family, a US official and Chinese state media said Wednesday.

Chen, who riled Chinese authorities by exposing forced abortions and sterilisations under the "one-child" policy, fled house arrest last week and reportedly sought refuge in the embassy.

China has demanded that the United States apologise for sheltering Chen Guangcheng in the US embassy in Beijing, the official Xinhua news agency said on Wednesday.