Prime Minister Prayut Chan-o-cha threatened to arrest political party leaders who speak against the draft constitution: "Do you understand the word 'power'?". Meanwhile officials showed the actual ballot to be used in the scheduled Aug 7 referendum. (Photos by Thanarak Khunton and Pornprom Satrabhaya)

Prime Minister Prayut Chan-o-cha has blasted political parties over their opposition to the draft constitution and the extra question in the referendum, telling them to leave the issue to voters.

The National Council for Peace and Order (NCPO) also warned political parties to toe the line following the Democrat Party's press briefing on Sunday, or they would face a summons.

The regime's aggressive reaction came after the two largest political parties came together to voice their opposition to the draft charter and the extra question which could pave the way for the appointed Senate to intervene in the selection of a prime minister after an election.

Democrat leader Abhisit Vejjajiva held a press briefing on Sunday to express the party's opposition to the draft charter and the extra question but did not comment on whether the party would actually reject the document in the referendum set for Aug 7.

Simple enough for you? Election Commissioner Somchai Srisutthiyakorn unveils a sample ballot for the referendum scheduled for Aug 7. (Photos by Thanarak Khunton)

The Pheu Thai Party has called for the draft charter to be rejected.

Gen Prayut said Monday that while politicians and parties had opinions on the charter and the extra question so did voters. He also said he believed a considerable number of people were on his side.

"They can't disagree with me, because it is not my opinion, it's the referendum. There are a lot of people who are with me on this," he said.

According to Gen Prayut, politicians oppose the draft because they are worried they will be unable to have their way. They want things to be like they were in the past.

"But let me ask this: have they used the power given to them by the people correctly? They just let [problems] go unsolved when they were in power," he said.

Gen Prayut also rejected the Democrats' call for the military regime to outline clear steps to be taken if the charter was shot down by voters and also threatened to arrest politicians if they tried to rig the vote.

"In that case, it is I who will have the power to decide what to do. Do you understand the word 'power'? It is I who will decide what to do."

Gen Prayut said he was not worried about political groups opposing the referendum and brushed aside a request by political parties to hold a debate on the draft charter.

"What will they do if I do not give permission? Do they want to be arrested? Those who break the [referendum] law will get up to 10 years in jail. Keep that in mind," he said.

National Council for Peace and Order (NCPO) spokesman Piyapong Klinpan said while the regime did not bar political parties from expressing their opinions, they should refrain from comments or activities deemed to affect national security or public order.

He said if a party's next move was deemed to compromise national security, those responsible would be summoned and enrolled in a "training course".

Meanwhile, Democrat members on Monday called on Gen Prayut and the NCPO to stay calm, saying the party's criticism was made in good faith.

Wirat Kanlayasiri, head of the Democrats' legal team, said if Gen Prayut listened carefully he would see the criticism was for the good of the public.

"It doesn't mean the party has an ill-intention when it gives different opinions," he said.

Meanwhile, Deputy Prime Minister Wissanu Krea-ngam said after meeting Election Commission (EC) members that the referendum will take place on Aug 7 between 8am and 4pm.

The cabinet will consider today if it will endorse the 2.99 billion baht budget proposed by the EC to organise the referendum.

"Anyone can tell others to accept or reject the draft charter as long as their intention is not to distort information," he said.

"Political parties can hold a press briefing to accept or reject the draft charter if they do not break the law, by using rude words, causing division or violence," he added.

He said the extra question set by the National Legislative Assembly could not be changed.

Mr Wissanu said the EC will issue regulations on what can be done ahead of the referendum.

Constitution Drafting Committee chairman Meechai Ruchupan said he was concerned about attempts to distort the content of the draft and cause misunderstandings.

Mr Meechai said enforcement of referendum legislation was likely to help avert distortion and called on the EC to strictly enforce the law.