The Pakistani government has blocked access to YouTube because of what it considers sacrilegious content on the video-sharing website.
The Pakistan Telecommunications Authority did not point to specific material on YouTube that prompted it to block the site on Thursday, citing only "growing sacrilegious contents."
It is the second time in two days that the government has restricted access to internet sites it deems offensive to the country's majority Muslim population.
On Wednesday, it blocked access to Facebook because of a page that invited users to submit drawings of Prophet Muhammad, which is a violation of Islam.
In both cases, the government took action after it failed to persuade the websites to remove the "derogatory material," the regulatory body said in a statement.
It welcomed representatives from the two websites to contact the Pakistani government to resolve the dispute in a way that "ensures religious harmony and respect."
The regulatory body said it has blocked more than 450 internet links containing offensive material, but it is unclear how many of the links were blocked in the last two days. Access to the online encyclopedia site Wikipedia and the photo sharing site Flickr was also restricted Thursday.
YouTube attracts just over two billion video views every day from users in more than 200 countries, the Google-owned company announced Monday.
Facebook also blocked
The government blocked Facebook on Wednesday after a group of Islamic lawyers won a court order requiring officials to restrict access to the site until May 31.
Facebook said Wednesday it was investigating the controversial page.
"While the content does not violate our terms, we do understand it may not be legal in some countries," the company said in a statement. "In cases like this, the approach is sometimes to restrict certain content from being shown in specific countries."
It remains to be seen how successful the government will be at keeping Pakistan's nearly 20 million internet users from accessing the blocked sites.
Other countries, such as China, permanently ban Facebook and YouTube. But citizens often have little trouble working their way around the ban using proxy servers and other means.
"What's common to Facebook and Lashkar-e-Taiba?" one user on Twitter wrote, referring to a Pakistani militant group. "They are both banned in Pakistan, but Pakistanis can still find them if they want to."