(CNN) -- Pakistan on Thursday blocked access to YouTube -- a day after it shut down the social networking site Facebook -- in response to an online group calling on people to draw the Prophet Mohammed.
The Pakistan Telecommunication Authority ordered operators to shut down YouTube "in view of growing sacrilegious contents on it," officials said in a statement.
PTA said Thursday it reached its decision after all "possible avenues were used within its jurisdiction, including using regular channels available on the Facebook and YouTube to launch protest, to avoid appearances of derogatory material available on their websites."
Facebook was blocked a day before "Everybody Draw Mohammed Day," which was scheduled by several Facebook groups dedicated to the idea.
The largest of the groups was unavailable for several hours Wednesday and Thursday.
Facebook said "a small technical issue prevented some users from accessing this page and others for a very short period of time," and that Facebook had corrected the problem as quickly as possible once they became aware of it.
"While it may be considered objectionable to some, the Facebook Pages and Groups in question do not violate our policies," Facebook global communications director Debbie Frost said.
The page was online as of Thursday morning Eastern time.
Frost said Facebook was "very disappointed" to be blocked in Pakistan.
"We are analyzing the situation and the legal considerations, and will take appropriate action, which may include making this content inaccessible to users in Pakistan," she said.
Khoram Ali Mehran of Pakistan's telecommunication authority said the block "is related to the objectionable material that was placed on Facebook."
"We have blocked it for an indefinite amount of time. We are just following the government's instructions and the ruling of the Lahore High Court. If the government decides to unblock it, then that's what we will do," he said.
The telecommunication authority has not received any complaints from Internet users about the blocking of Facebook, he said.
Devout Muslims consider it offensive to depict Mohammed.
There were riots around the world in response to a series of cartoons of Mohammed in a Danish newspaper in 2005, and at least two European cartoonists live under police protection after publication of their drawings of the Muslim prophet.
Mimi Sulpovar, who started one of the Facebook groups, said she read about the idea on a blog after Comedy Central bleeped out part of an episode of "South Park" that mentioned the prophet.
"This is meant to be in protest," she said.
"This is something I have felt strongly about for a long time: Bullying by certain Muslim groups will not be tolerated in a free country," said Sulpovar, who is American.
But Ibrahim Hooper, a spokesman for the Council on American-Islamic Relations, said the idea behind the group was offensive.
"Islam discourages any visual representations of the prophets of God -- Jesus, Moses, Mohammed, anybody -- because we believe it can lead to a form of idol worship," he said.
"The majority of Muslims worldwide object to any representation of a prophet of God," he added.
The idea of "Draw Mohammed Day" originated with a cartoonist who has since distanced herself from the idea, Sulpovar and Hooper said.
"The whole campaign has been taken up by Muslim-bashers and Islamophobes," Hooper said.
But Sulpovar denied being anti-Muslim.
"This extends beyond being able to draw Mohammed," she said. "If it's offensive to you, that's fine, but I don't feel it's right to impose your belief on others through intimidation.
"This is nothing to do with hate or bigotry," she said. "Nobody is inciting violence or preaching open hatred towards individuals."
Sulpovar said she is not a Muslim but added that she had received "hundreds of e-mails from people trying to explain this to me."
One group member said she saw anger and fear on both sides of the controversy but felt that free speech could not be compromised.
"This is a hot-topic debate, but so is abortion, illegal immigrants, gay marriage and politics. If we allow even a small compromise for one group, then the free speech on topics like abortion, illegal immigrants and politics can also be censored based on accusations that they cause violence or hate," Autumn Meadows said on CNN's iReport.
"Hate speech is wanting a group eradicated, physically harmed or dead. I don't think drawing Mohammed falls under that category," she said.
"Islam is not above criticism or cartoons. I believe in equality, and censoring Mohammed while we can draw every other figure in the world does not equal equality," she concluded.
Sulpovar said Pakistan's decision to block Facebook was "ridiculous."
Sulpovar's group had attracted more than 9,000 fans as of Thursday morning. The page which disappeared briefly had more than 80,000 fans.
Groups opposing the idea had about 68,000 fans as of Wednesday.
Facebook is investigating the block, said Frost, the communications director.
"We want Facebook to be a place where people can openly discuss issues and express their views, while respecting the rights and feelings of others," she told CNN.
"We sometimes find people discussing and posting about topics that others may find controversial, inaccurate, or offensive. When these feelings, or any content reported to us becomes an attack on anyone, including Muslim people, it will be removed and further action may be taken against the person responsible," she said.