Prime Minister Prayut Chan-o-cha on Wednesday issued his sternest warning yet to protesters seeking his resignation, saying they were creating deeper divisions that could cause the collapse of the country.
"If we want to overcome each other politically, the nation will collapse," Gen Prayut told reporters.
"If that happens, just wait, everybody will be on fiery land, engulfed in flames."
His comments come after a month of near-daily rallies led by students calling for his ouster, a new constitution and fresh election, with some drawing over 10,000 protesters.
Some of those demonstrators have openly called for reforms of the country's monarchy, a taboo topic in a country with a strict law that punishes perceived royal insults with up to 15 years in prison.
"I am at my wits end," Gen Prayut added.
Earlier on Wednesday, police expanded a crackdown on protest leaders with the arrest of Tattep Ruangprapaikitseree and Panumas Singprom of the Free Youth Group.
Separately, a minister said the government is pushing for the removal of 1,000 online posts, videos and other content that "breaks the law", after Facebook vowed legal action over the censorship of a group discussing the monarchy.
A private Facebook group called "Royalist Marketplace" had more than a million members posting about the royal family before it was blocked in Thailand on Monday.
The social media giant said it was "compelled" by the government to block the group, and is preparing to mount a legal challenge against the move.
But the Ministry of Digital Economy and Society now wants to obtain court removal orders relating to 1,024 more URLs on Facebook, Twitter, Youtube and five other sites, minister Buddhipongse Punnakanta told reporters.
The offending pages allegedly broke the Computer Crimes Act, which has a five-year maximum jail penalty and is often used to stifle dissent online.
"We have not violated anyone's rights... but if they break the law they will face legal action," the minister said.
He denied that "Royalist Marketplace" was removed for political reasons, saying simply that the ministry "must protect Thailand's cyber sovereignty".
Moderator Pavin Chachavalpongpun -- a Thai critic who was granted asylum in Japan -- started a new Facebook group which so far has 730,000 members, he said.
Complying with the order "jeopardises democracy and strengthens the government's grip on information control", Pavin told AFP.
"If Facebook accepts the request, it would become a part of the rising authoritarian trend in Thailand."