Of the known affected pages, 21 are based in Brazil, and four are English-language pages, with administrators in the U.S. and Africa. Most of the blocked pages had significant followings - between hundreds of thousands and up to 6 million followers each.

One of the blocked English-language fanpages was "Jesus and Mary", which had 1.7 million followers. The page's main cover photo was of the sacred hearts of Jesus and Mary.

Page administrator Godwin Delali Adadzie, a Ghanaian, told CNA he was on Facebook around 8 p.m. Central July 17 when he was asked to upload a photo of himself because his personal account had been "suspected of suspicious activities," he said. 

After several minutes, he was allowed back into his personal account, which had notifications informing him that his "Jesus and Mary" page had been disabled. He said every person who was approved as an editor on his page had to go through the same process.

Adadzie said he reviewed Facebook's policies "and, honestly, I do not see any that I have violated in order for my page to be withdrawn."

He has sent two appeals to Facebook but has yet to get a response.

Another blocked English-language page is "Catholic and Proud", which had 6 million followers. Page administrator Kenneth Alimba of Nigeria told CNA his page was also blocked without explanation.

He has sent appeals to Facebook but is "not optimistic" about a response. He also told CNA that he noticed other Catholic Facebook pages that he runs, with fewer followers, are still online.

Another blocked English-language page is "Fr. Rocky," belonging to U.S. priest Father Francis J. Hoffman, executive director of Relevant Radio, whose page had 3.5 million likes. Fr. Hoffman could not be reached for comment by press time. 

Facebook has yet to respond to requests for comment on the blocked pages. Facebook is the largest social network in the world, having recently reached more than 2 billion users.

While it remains unknown why these pages were blocked, some of the page administrators have said they wonder whether they are being censored.

In 2016, Facebook came under fire for allegedly censoring trends to news deemed "conservative."

On that occasion, Mark Zuckerberg rejected the allegations of censorship, and met with conservative U.S. leaders to assure them Facebook's neutrality.

In the past, user accounts have also been inadvertently blocked on Facebook due to system glitches, or numerous complaints against the page in a short time period. In these cases, Facebook restored the accounts after reviewing their content.

Brantly Millegan contributed to this report.