Twitter declined to comment, while Facebook and Google did not respond
Thailand began legal action on Thursday against Facebook and Twitter for ignoring requests to take down content, in its first such move against major internet firms.
The digital ministry filed legal complaints with cybercrime police after the two social media companies missed 15-day deadlines to comply fully with court-issued takedown orders from August 27, the digital minister, Puttipong Punnakanta, said.
No action was taken against Alphabet's Google as originally suggested, as it took down all the YouTube videos specified in the order late on Wednesday, Puttipong said.
"This is the first time we're using the Computer Crime Act to take action against platforms for not complying with court orders," Puttipong told reporters.
"Unless the companies send their representatives to negotiate, police can bring criminal cases against them. But if they do, and acknowledge the wrongdoing, we can settle on fines."
He did not disclose details of the content or say what laws it had violated. The complaints were against the US parent companies and not their Thai subsidiaries, he said.
The ministry will file more such takedown requests to Facebook, Twitter, and Google, asking them to remove more than 3,000 items from their platforms, with content ranging from pornography to criticism of the monarchy, Puttipong said.
Twitter declined to comment, while Facebook and Google did not respond to Reuters' requests for comment.
Thailand has a tough lese majeste law that prohibits insulting the monarchy. The Computer Crime Act, which outlaws the uploading of information that is false or affects national security, has also been used to prosecute online criticism of the royal family.
In recent years, authorities have filed court orders with requests to social media platforms to restrict or remove perceived royal insults and other illegal content like gambling or copyright violations.
Under the Act, ignoring a court order can result in a fine of up to $6,347, then $159 per day until the order is observed.
The ministry also filed separate cybercrime complaints against five people who it said criticized the monarchy on Facebook and Twitter during a major anti-government demonstration at the weekend, Puttipong said.