DTAC was ordered to restrict its customers from accessing Facebook on May 28 by the National Council for Peace and Order (NCPO), according to a representative of Telenor Group of Norway, DTAC's major shareholder.
Telenor Asia vice-president Tor Odland wrote an e-mail to Aftenposten, a Norwegian newspaper, that the company received a call from the National Broadcasting and Telecommunications Commission, which has been under the NCPO since the May 22 coup, to temporarily prevent its customers from entering Facebook.
The restriction was carried out at 3.35pm, impacting around 10 million DTAC users, according to Mr Odland.
He also added that the situation puts Telenor in a conundrum. Being an international mobile operator, uphold human rights. However, doing so might conflict with Thailand's regulations.
"There is no doubt that such cases put a mobile operator under Telenor in a demanding situation. On the one hand we relate to international frameworks such as the UN guidelines on human rights and business. On the other hand, we have that licensee's duty to deal with local laws," wrote Mr Odland.
At 3pm on May 28, people across Thailand could not enter the social media site for about 30 minutes. After the incident, Information and Communication Technology permanent secretary Surachai Srisarakam released a statement that it temporarily blocked Facebook by order of the NCPO.
However, NCPO deputy spokesman Nathawat Chancharoen denied the claim.
"There's no need for the NCPO to block Facebook. And even if we wanted to, we would have to make an announcement first," said Col Nathawat.