A senior Thai general has told the BBC that last month's military coup had not been planned in advance.
It comes after an opposition leader claimed the army had been discussing overthrowing the government for years.
Lt Gen Chatchalerm Chalermsukh also said those detained by the military since the coup were being treated well.
And he said controversial former PM Thaksin Shinawatra and his family could still return to Thai politics.
Thai soldiers march while changing positions with fellow soldiers on a street in Bangkok, Thailand on May 29. Photo: AP
The military seized power in the south-east Asian nation on 22 May, saying it wanted to return stability to Thailand after months of political and social unrest.
It has promised a return to democracy, but only after it has carried out sweeping reforms of the political system.
Coup leaders, led by army commander Gen Prayuth Chan-ocha, said they intervened at the last minute to stop the country sliding into a more dangerous and violent political conflict.
However in a recent interview one of the main supporters of the coup, protest leader Suthep Thaugsuban, said he had discussed overthrowing the government with Gen Prayuth many times in recent years.
'Forces in place'
"So far as I know there was no advanced planning," Gen Chatchalerm told the BBC's Jonathan Head.
"If it were planned that would be illegitimate. If you are wondering why this happened so smoothly, that was because forces were already deployed in the city [Bangkok]. So when we declared martial law, there were already joint military and police forces in place in the area, " said the general, who is army deputy chief of staff and a member of the National Council for Peace and Order that now governs Thailand.
But Gen Chatchalerm said the places where they were being held are "not really like places of detention".
"They are like guest houses," he said.
"There are no barbed wire fences, and we have showed these places to human rights groups. We even broadcast pictures of them on national TV. We showed interviews with some of the summonsed people. Everyone was satisfied with this."
He also suggested that the military would be lenient in pressing charges against those who have been arrested.
"When it gets to court - civilian or military - the punishment will not be that severe," he said.
Supporters of the coup alleged that the ousted government of Yingluck Shinawatra was controlled by her brother, Thaksin Shinawatra, who was prime minister until his removal by the military in 2006.
Thaksin was later convicted of corruption and lives in self-imposed exile.
The Shinawatra family enjoy strong support in rural and northern areas that has propelled them to successive election wins.
However, many in the middle class and urban elite oppose them bitterly, alleging they have corrupted Thai democracy with money politics.
Despite this, Gen Chatchalerm said it was still possible that Thaksin could return to politics after reforms are complete.
"When we reach the final stage, with a new election, the reforms will have been completed," he said.
"Everyone who is Thai and is qualified can take part in that election - even the family of Thaksin Shinawatra.
"You will see the way we run things - we are not hunting Thaksin, as we did before. He is free to do anything. We would like to see him come back and fight the legal charges against him. If he is confident he can win, then he will be able to return to politics."
Earlier this week, exiled Thai minister Charupong Reuangsuwan said he had formed a group to lead a campaign against the military government.
He is the only minister to have escaped into exile.
Charupong called the coup "an outrageous act" and "grand larceny".