The Pakistan Telecommunication Authority told the country's 70 Internet service providers on Friday that the popular website would be blocked until further notice.
A Pakistan Telecommunication Authority official said the ban was prompted by a movie trailer for an upcoming film by Dutch lawmaker Geert Wilders. Wilders has said he plans to release an anti-Koran movie portraying Islam as fascist and prone to provoking violence against women and gays.
The Pakistan Telecommunication Authority official, who spoke on condition of anonymity because he is not an official spokesman, said the authority also blocks websites that show controversial drawings of the prophet Muhammad. The drawings were initially printed in European newspapers in 2006 and were reprinted by several newspapers last week.
The Pakistan Telecommunication Authority pressed Web surfers to write letters to YouTube requesting that the anti-Islamic movies be removed. Authorities said they would lift the ban on the site after the movies were pulled.
According to The Washington Post, Pakistan is not the only country to have blocked access to YouTube.
A court in Turkey blocked access to the site in January because of video clips that insulted the country's founding father, Mustafa Kemal Ataturk. It is illegal to insult Ataturk in Turkey.
Thailand's government banned YouTube for about four months last spring because of clips that were deemed offensive to the country's revered monarch, King Bhumibol Adulyadej.
Morocco also blocked access to YouTube last year after users posted videos that were critical of the country's treatment of the people of Western Sahara, a territory Morocco took control of in 1975.