Facebook has not blocked more than 100 sites deemed to have insulted the monarchy or be a threat to national security as requested by the telecom regulator, citing the need for official court orders from authorities to do so.
Facebook users in Thailand can still access the sites despite the deadline to remove them passing.
The National Broadcasting and Telecommunications last week gave Facebook Thailand until 10am Tuesday to take down 131 URLs with content deemed insulting to the monarchy or threatening national security.
Failure to do so may result in legal action, the watchdog said.
Takorn Tantasith, secretary-general of the NBTC, went to the headquarters of the Thai Internet Service Provider Association [TISPA ] on Tuesday to inspect whether the 131 URLs had been blocked.
He later told reporters that Facebook had informed TISPA it had not received official court orders to block the URLs so it could not make them inaccessible in Thailand.
He said authorities had only sent court orders for 34 of the sites without providing details, and the US-based social media giant needs all the details.
Takorn said the Digital Economy and Society Ministry will request court orders for all 131 URLs and it will send them to Facebook.
Takorn said Facebook had committed itself to cooperating with authorities when it received the court orders.