Today’s Bangkok Post says:
Former prime minister Thaksin Shinawatra will begin a visit to Cambodia on Sept 16 to attend the Asian Economic Forum Conference, Cambodian Prime Minister Hun Sen said on Monday, Xinhua news agency reported on its website.
Hun Sen said Thaksin’s visit was scheduled before the official visit of Prime Minister Yingluck Shinawatra, who will make an official one-day visit to Phnom Penh on Thursday.
(Emphasis mine.)