The ministry would file complaints with cybercrime police on Thursday after the U.S. companies missed deadlines to comply fully with court-issued takedown orders, digital minister Puttipong Punnakanta said.
“We’ve notified the companies and sent them warnings twice, but they haven’t complied with all the requests,” Puttipong told Reuters.
He did not disclose details about the content or what laws it had violated. Representatives of the three companies were not immediately available for comment.
The ministry will also file separate complaints against 10 people who it said criticized the monarchy in social media posts during a major anti-government demonstration at the weekend, he said.
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 illegal content like gambling or copyright violations.
Under the Act, ignoring a court order can result in a fine of up to 200,000 baht ($6,347), then 5,000 baht ($159) per day until the order is observed.
The ministry on Aug. 27 asked Facebook to block 661 posts but it took down less than a third of those, Puttipong said.
Twitter and YouTube, owned by Alphabet, received requests that same day to restrict scores of posts, but have not acted on all of them, he said.
Facebook last month blocked access within Thailand to a group with a million members that discussed the monarchy, saying it was compelled to after Puttipong threatened legal action against its local office.