BANGKOK — Thailand has barred a top leader of Cambodia's opposition party from entering the country, casting doubt on plans for its exiled leaders to return to their homeland against the Cambodian government's wishes.

Mu Sochua, a former lawmaker of the court-disbanded Cambodia National Rescue Party, says she was deported Sunday after arrival at Bangkok's international airport.

Co-founder Sam Rainsy has declared that he and other exiled party colleagues plan to return to Cambodia on Nov. 9, along with a mass of Cambodian supporters who also live outside the country. While Thailand has never been publicly specified, it is the only practical location for such a plan.

Cambodian Prime Minister Hun Sen has said security forces would stop or arrest the would-be returnees, whom he has called traitors.