It is not necessary for the government to impose the Internal Security Act tomorrow, when the red-shirt Radio Broadcasters for Democracy group claims up to 100,000 people will join its rally outside the Constitution Court, National Security Council chief Lt-Gen Paradorn Pattanatabut said on Tuesday.
The NSC chief said it was believed the red-shirts were unlikely to cause problems, and police would see to it that protesters of opposite sides would not clash.
There were also no reports of possible interference by a third party.
"It is, therefore, not necessary to impose the Internal Security Act or a special law to control the protest," Lt-Gen Paradorn said.
The red-shirts of the Radio Broadcasters for Democracy movement have maintained a small rally outside the Constitution Court for over two weeks, demanding all nine court judges resign.
Charn Chaiya, a leader of the movement, said the group would cancel its rally if the gathering failed to draw up to 100,000 participants.
Deputy Commerce Minister Nattawut Saikuar, a leader of the United Front for Democracy against Dictatorship, said there was nothing to worry about since the rally leaders had affirmed the gathering would be peaceful.
They were only calling for the Constitution Court judges to show responsibility for their actions, he said.