(CNN) -- An apparent move by the Pakistani government to block YouTube, the popular video-sharing Web site, knocked out access to the site worldwide for more than two hours, Internet analysts say.
An Internet cafe in Islamabad, Pakistan
The outage followed a letter sent Friday evening by the Pakistani Telecommunications Authority (PTA) to Internet service providers, ordering them to prevent people in Pakistan from visiting YouTube.
The authority cited a "highly blasphemous" video featuring right-wing Dutch politician Geert Wilders.
The block was intended to cover only Pakistan but extended to about two-thirds of the global Internet population, The Associated Press cited Renesys Corp, an Internet monitoring company, as saying.
What happened was that Pakistan Telecom established a route that directed requests for YouTube videos from local Internet subscribers to a "black hole," AP cited Renesys as saying. It then published that route to its international data carrier, PCCW of Hong Kong, which accepted, AP quoted Todd Underwood, vice president of Renesys, as explaining.
The move also coincided with the temporary shutdown Friday evening of Aaj TV, a Pakistani television cable and satellite channel, after it reportedly upset President Pervez Musharraf. Since declaring a nationwide state of emergency on November 3, he has taken independent television stations off the air; they would later be allowed to resume service.
In YouTube's case, it was completely inaccessible on Sunday from 10:48 a.m. PT to 12:51 p.m. PT (11:48 p.m. Sunday to 1:51 a.m. Monday in Pakistan), said Shawn White, a spokesman for Keynote Systems, a San Mateo, California-based Internet-performance monitoring company.
Keynote Systems' monitoring of major Web sites like YouTube includes attempting to access them every 15 minutes from computers in 35 cities in Europe, Asia and the Americas, White said.
"I was kind of surprised that something like this could happen, especially globally," said White, calling the outage the most high-profile Internet blackout he remembers in his 12 years with the company. "It just further illustrates just how fragile the Internet can be.
"There are a lot of protocols and checks and guidelines in place that all of these international Internet service providers are supposed to follow," White said. "In this scenario, it's like someone made a change and didn't realize the change they were making was going to affect everyone around the world."
White added that his company's monitors additionally noted about a one-hour period -- starting at about 7 a.m. PT on Monday -- during which YouTube service slowed down dramatically. He said the cause of that slowdown wasn't yet clear.
In a statement released on Monday, YouTube did not mention the Pakistani government's move to block access to the site but attributed the outage on Sunday to an issue related to its site in Pakistan.
"Traffic to YouTube was routed according to erroneous Internet protocols, and many users around the world could not access our site," the statement said.
"We have determined that the source of these events was a network in Pakistan," YouTube added. "We are investigating and working with others in the Internet community to prevent this from happening again."
In a statement on its Web site, the PTA said the video had "the potential to cause more unrest and possible loss of life and property across the country."
"PTA believes that the said footage absolutely stands against the values of religious tolerance and peaceful co-existence arousing deep anguish and distress across the Muslim world."
Wilders, a far-right Dutch lawmaker, announced last month that he would release an anti-Islam film. Both the U.S. Department of Homeland Security and the FBI have expressed concern that the film would spark global protests and riots.
The Pakistan government is asking YouTube to remove the "objectionable content," said Nabiha Mehmood, a spokeswoman for the PTA.
The government said it decided to block the video after senior representatives from several ministries of the Pakistani government met, according to a statement on the PTA Web site.
The authority sent the letter to Internet service providers after the meeting, Mehmood said, adding that the government would reinstate access to the video-sharing site if YouTube complied with the request.
The decision in Pakistan received mixed reactions.
"Some people are quite upset and screaming. They say they have been using YouTube regularly," said Wahal us Siraj, one of the founders of the Internet Service Providers Association of Pakistan, and chief executive officer of Micronet Broadband. "There are others who say that YouTube is full of videos... that are damaging to the character of children."
Roughly 3 million to 5 million of Pakistan's 165 million people have Internet access, according to Siraj's association.
The recent reprinting in European newspapers of the controversial cartoon of the Prophet Mohammed that sparked worldwide protests two years ago has inflamed emotions further.
The 3-year-old YouTube has exploded in popularity by letting ordinary people post their own videos online and watch videos that others have posted. The Web site's growth also has spawned efforts around the world to regulate it.
Authorities in Brazil, China, Iran, Morocco, Myanmar, Syria and Thailand have blocked access to YouTube in the last few years, according to Reporters Without Borders, a press advocacy organization.
The countries acted after concluding that YouTube videos were subversive (China), immoral (Iran), embarrassing to well-known figures (Brazil) or critical of a country's king (Thailand), the group said.
Governments also have sought to regulate user-supplied Internet content to stymie allegations that they abuse human rights, the group said.
A few months ago, YouTube, responding to complaints, took down videos posted by an award-winning Egyptian human rights advocate that showed what he described as police abuse. About five months later, after media reports, YouTube restored his account and let him continue posting videos.
YouTube is a subsidiary of Google Inc., which bought the site in 2006 for nearly $1.7 billion.