Officials will summon nine suspects charged with posting content contravening the lese majeste law on social media last year for interrogation this month, says the Ministry of Digital Economy and Society (DES).
Buddhipongse Punnakanta, the minister responsible for the DES, said on Tuesday there would be no feet dragging over pursuing prosecutions against those responsible.
The DES first alerted the Royal Thai Police's Technology Crime Suppression Division (TCSD) in November, which began the process of making contact with the administrators of the social media sites to warn them they were hosting material violating Section 112 of the Criminal Code.
It also asked them to hand over details of those accounts responsible.
The DES had found a total of 638 URLs which it considered illegal between October and December last year violated the Computer Crime Act 2007.
DES officials also found that 26 internet accounts had been responsible for the majority of them.
"We have identified nine individuals who are owners of these accounts.
They are not new faces and have been charged with similar offences many times before," he said.
Meanwhile, the ministry will also pursue legal action against social media giants Facebook and Twitter for failing to comply with the law and remove illegal content viewable in Thailand.
The DES found 8,443 URLs which it considered to harbour illegal content, with 5,494 on Facebook pages and the rest on Twitter.
Facebook agreed to the removal of 3,107 links, while Twitter refused 611 of the requests. The ministry is unhappy with the partial response and plans action.
He said the attorney-general has already decided to pursue the case against Facebook once investigations conclude.