BANGKOK (REUTERS/AFP) - Thailand's information technology ministry blocked Facebook on Wednesday and planned to hold talks with other social networking sites to stem protests against the military government, a senior official said.

"We have blocked Facebook temporarily and tomorrow we will call a meeting with other social media, like Twitter and Instagram, to ask for cooperation from them," Surachai Srisaracam, permanent secretary of the Information and Communications Technology Ministry, told Reuters.

"Right now there's a campaign to ask for people to stage protests against the army so we need to ask for cooperation from social media to help us stop the spread of critical messages about the coup," he said.

Print and broadcast media have already been instructed to refrain from critical reporting of the military's May 22 takeover.

But earlier, the junta quickly denied imposing the block in response to media queries as Facebook users reacted with alarm after experiencing widespread problems accessing the social networking site.

"Urgent: Facebook has been suspended," one user wrote on Twitter.

"Surely that would be suicide. Whole country would protest," wrote another user.

But just minutes later users celebrated: "Facebook is back!!"

Army spokesman Colonel Winthai Suvaree told AFP that they have not ordered a block of Facebook, adding that "it's not our policy".

"Facebook experienced a slight technical failure and the Ministry of Information and Communication Technology is working to fix it now," he said.

But some users were unconvinced, speculating that it could have been a trial run for a possible blackout in the future, or a warning shot to social media users not to criticise the coup.

Social media platforms such as Twitter and Facebook are hugely popular in the country. The junta has warned it would block any social media platforms found to carry content that incites violence or is critical of its military leaders.