However, he told reporters that observers would be invited for the next general election.

The UN issued a statement on Tuesday saying it was ready to support Thailand in this critical juncture to facilitate a swift return to democracy, while underlining an open and inclusive debate ahead of the referendum. The plebiscite is considered essential to ensure the legitimacy of the draft charter and achieve national unity.

The statement came in the wake of Prime Minister Prayut Chan-o-cha’s phone conversation on Monday with UN Secretary-General Ban Ki-moon, in which the UN was updated about political moves in the country.

This was done at around the same time the red-shirt United Front for Democracy against Dictatorship (UDD) submitted a petition to the UN Office of the High Commissioner for Human Rights in Bangkok requesting that it monitor the referendum on the draft charter.

Prayut said he welcomed the UN’s support, but appeared to be reluctant to discuss the monitoring of the referendum. He only told reporters: “I don’t answer ‘if’ questions.”

Wissanu, meanwhile, said he had learned from Constitution Drafting Commission (CDC) chairman Meechai Ruchupan that volunteers disseminating charter content were being threatened, and said he would step up security to ensure their safety.

He said anybody who witnesses such threats can file a police complaint to protect the volunteers.

Separately, New York-based Human Rights Watch issued a statement on Tuesday calling for the revocation of restrictions on free expression in order to ensure a fair referendum that is up to international standards. Meechai responded to the statement by saying only comments deemed vulgar, aggressive and violent were prohibited.

“Do you think vulgar or aggressive comments are acceptable? You would know what it’s like for sure if somebody did this in front of your office,” he said.