The army's latest order, announced on local television on Sunday, calls for all organisations to end political gatherings "until the situation returns to normal".
The coup leader's have also said they will give a panel they set up to investigate corruption under former prime minister Thaksin Shinawatra's rule the power to seize assets.
"There is sufficient evidence to believe that [members of the former government] abused their power to reap benefits for their personal gain, and caused serious damage to the country," said an announcement on television.
The Thai authorities have imposed martial law and public gatherings of more than five people are banned.
An army spokesman said politicians in the northern town of Chiang Mai, Thaksin's hometown, were critical of the coup and had been holding meetings.
Community radio stations in the area have also been closed down.
Students at Thammasat University in Bangkok have said they plan to hold a meeting potentially critical of the coup.
Thailand's king is to confirm the country's interim prime minister on Wednesday, according to a military spokesperson.
Half a dozen highly regarded figures - including lawyers, technocrats and a UN agency chief - have been cited by the local press and diplomats as possible candidates for the job.
The short-listed candidates are Ackaratorn Chularat, the Supreme Court president; Supachai Panitchpadki, who heads the UN conference on trade and development; Pridiyathorm Devakula, chief of Thailand's central bank; Chatumongkolnakul, the former finance minister and Charnchai Likhitjittha.
"If anyone commits wrongdoing, they will have to be prosecuted in the courts"
Thai anti-corruption commission
All are regarded as corruption-free and either politically neutral or on record as having opposed Thaksin's regime.
On Sunday, Parnthep Klanarongran, the new chief of the Counter Corruption Commission, which faces a backlog of about 10,000 cases, including several potentially involving Thaksin, said: "Any cases that cause serious damage to the country, we will have to investigate urgently.
"If anyone commits wrongdoing, they will have to be prosecuted in the courts."
Thaksin's critics charge that the former prime minister, a telecommunications tycoon before becoming a politician, used his high office to enrich himself and his associates.
Thaksin's family is one of the wealthiest in Southeast Asia.
In January, Thaksin sold his Shin Corp to Singapore's state investment company, Temasek Holdings, for a reported $1.9 billion tax-free deal.
Critics, who allege that the sale involved insider trading, also complain that a major national asset is now in a foreign government's hands.
A high-ranking official has said that some of Thaksin's wealth can be seized if an investigation determined that he illicitly profited from his position.
Critics say Thaksin used his office
to enrich himself and friends
"The assets and money he had before he became prime minister will not be touched," said an official, who requested anonymity.
An interim constitution to temporarily replace the 1997 one scrapped by the junta is being drafted and is expected to be completed within days, local press reports said on Saturday.
The document, according to the reports, spells out the process for drafting and enacting a new permanent constitution so an elected government can be re-established in about a year's time.