Members of hardline Islamic parties held rallies throughout Pakistan on Friday to protest caricatures of the Prophet Muhammad on the social networking website Facebook
Demonstrators shouted anti-American slogans and burned U.S., Danish and Swedish flags as they took to the streets in the eastern city of Lahore and the southern port city of Karachi.
The Pakistani Telecommunications Authority has banned access to Facebook, Youtube and more than 450 links containing "sacrilegious" content and derogatory material.
Facebook is blocked until May 31 because it carries a controversial page that encourages users to draw the Prophet Muhammad.
The social networking site says it is considering whether to make the offending page inaccessible in Pakistan.
Most Muslims consider any image of the Prophet Muhammad to be blasphemous.
The CEO of Pakistani Internet service provider Nayatel, Wahaj-us-Siraj, told VOA on Thursday that the government will reopen access to the sites once Facebook and YouTube remove the controversial material.
Pakistan temporarily blocked YouTube in 2008 because a movie trailer on the site portrayed the Muslim holy text, the Koran, as a fascist book.
Angry protests swept across Muslim countries in 2005 and 2006 after a Danish newspaper printed several caricatures of Muhammad.