By Wednesday evening, access to the site was sporadic, apparently because Internet providers were implementing the order.
The Facebook page at the center of the dispute — "Everybody Draw Mohammed Day!" — encourages users to post images of the prophet on May 20 to protest threats made by a radical Muslim group against the creators of "South Park" for depicting Muhammad in a bear suit during an episode earlier this year.
In the southern city of Karachi, about 2,000 female students rallied demanding that Facebook be banned for tolerating the page. Several dozen male students held a rally nearby, with some holding signs urging Islamic holy war against those who blaspheme the prophet.
"We are not trying to slander the average Muslim," said the information section of the Facebook page, which was still accessible Wednesday morning. "We simply want to show the extremists that threaten to harm people because of their Mohammad depictions that we're not afraid of them. That they can't take away our right to freedom of speech by trying to scare us into silence."
A series of cartoons of the prophet published in a Danish newspaper in 2005 sparked violent protests by Muslims around the world, including Pakistan, and death threats against the cartoonists.
Facebook said Wednesday it is investigating.
"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 move will be at keeping people in Pakistan from accessing the site. Some countries, such as China, permanently ban Facebook. But citizens often have little trouble working their way around the ban using proxy servers and other means.
In an attempt to respond to public anger over the Facebook controversy, the Pakistani government ordered Internet service providers in the country to block the page Tuesday, said Khurram Ali, a spokesman for the Pakistan Telecommunications Authority.
But the Islamic Lawyers' Forum asked the Lahore High Court on Wednesday to order the government to fully block Facebook because it allowed the page to be posted in the first place, said the deputy attorney general of Punjab province, Naveed Inayat Malik.
The court complied with the request and ordered the government to block the site until the end of May, Malik said.
Lawyers outside the courtroom hailed the ruling, chanting "Down with Facebook."
Later in the day, the telecommunications authority ordered all Internet service providers to block Facebook, it said in a statement.
Pakistan's minister of religious affairs, Hamid Saeed Kazmi, said the country's ban was only a temporary solution and suggested the government organize a conference of Muslim countries to figure out ways to prevent the publication of images of the prophet, which have caused backlashes among Muslim populations.
On Tuesday, an alleged al-Qaida militant detained in Iraq said he had talked to friends about attacking Danish and Dutch teams at the World Cup in South Africa next month.
"We discussed the possibility of taking revenge for the insults of the prophet by attacking Denmark and Holland," Abdullah Azam Saleh al-Qahtani told The Associated Press in an interview arranged by Iraqi authorities. "The goal was to attack the Danish and the Dutch teams and their fans."
In the Netherlands, an anti-Islam party has become the country's fastest growing political movement. Its leader, Geert Wilders, calls the Quran a "fascist book" and wants it banned in the Netherlands. His 2008 short film offended many Muslims by juxtaposing Quranic verses with images of terrorism by Islamic radicals.
