Former Interior Minister Charupong Reuangsuwan said Tuesday in an open letter read on YouTube and posted on Facebook that the Organisation of Free Thais for Human Rights and Democracy rejects the junta's legitimacy.
Charupong led the Pheu Thai Party that won the 2011 election. Its opponents launched aggressive street protests last year to demand it hand over power to an appointed government that would make reforms.
The army ousted the elected government in a coup on May 22, and Charupong defied its order to surrender, apparently fleeing to neighbouring Cambodia.