Ms Yingluck will arrive at Suvarnabhumi airport on a private jet from Singapore, the source said. Other reports said she would land at Don Mueang Airport.
Paethongtan Shinawatra, Thaksin's eldest daughter, earlier posted a group photo of Thaksin, Ms Yingluck and Somchai Wongsawat, Thaksin’s brother-in-law, on her @ingshin21 Instagram account, with an accompanying message saying “Sunday … a family day”.
The photo of the three former prime ministers was taken at an undisclosed restaurant.
Ms Yingluck left Thailand for a holiday in Europe and the United States after she was granted permission to leave the country between July 23 and today. She was required to request permission because of pending legal allegations against her.
A few days before her scheduled return date of Aug 10, there had been reports Ms Yingluck had written to junta chief Prayuth Chan-ocha asking for her return to be deferred until the end of the month. Lt Gen Kampanat Ruddit, director of the NCPO’s Centre for Reconciliation and Reform, said the reports were unfounded. Ms Yingluck had not made any such request and her schedule remained unchanged.
During her overseas trip, Ms Yingluck attended the 65th birthday celebrations on July 26 for her brother Thaksin in Paris. Speculation has been rife that she might stay abroad rather than return to face charges of dereliction of duty in connection with her government's failed rice-pledging programme.