Kim Jong-Nam was sighted at an Italian restaurant run by a Japanese businessman in Jakarta on May 4 with two women, cable news network YTN said.
YTN quoted one of Kim's friends as saying the 43-year-old had been living well, shuttling back and forth among Singapore, Indonesia, Malaysia and France, despite the shock execution of his uncle, Jang Song-Thaek, last December.
Kim Jong-Nam was reportedly close to Jang, once the North's unofficial number two and political mentor of current leader Kim Jong-Un.
Kim Jong-Nam was once considered heir apparent but fell out of favour with his father following a botched attempt in 2001 to secretly enter Japan and visit Disneyland.
He has since lived in virtual exile, mainly in the Chinese territory of Macau.
Kim Jong-Nam, known as an advocate for reform, once told a Japanese newspaper that he opposed the idea of the North's dynastic power transfer.