July 30 (Reuters) - Elon Musk dismissed as "fake news" a report that executives at his electric vehicle company Tesla have been told to prepare for a separation of its China business ahead of a potential merger with his space exploration firm SpaceX. "This has never even come up in a discussion ever," Musk, the world's richest person, said on ​his X social media account in response to the report. Tesla and SpaceX could not be immediately reached for comment outside regular business hours. Last week, Musk declined to dismiss the possibility of a merger between Tesla and his other trillion-dollar-plus company, SpaceX, saying the two businesses are increasingly overlapping. Unlike many foreign automakers, Tesla's Chinese vehicle business is not structured as a joint venture with a ​local ​partner.