The Pakistan Telecommunication Authority (PTA) directed Internet service providers to block Facebook indefinitely on Wednesday because of an online competition to draw the Prophet Mohammad.
The order followed a decision by the Lahore High Court temporarily banning Facebook in Pakistan after the country's media reported that the competition would be held on May 20.
The court has ordered the government to immediately block Facebook until May 31 because of this blasphemous competition, Azhar Siddique, a representative of the Islamic Lawyers Forum who filed a petition in the Lahore High Court, told Reuters.
The court has also ordered the foreign ministry to investigate why such a competition is being held.
A spokesman for the PTA, the country's telecommunication watchdog, said the government on Tuesday ordered Internet providers to block only the Facebook page showing these caricatures. But on Wednesday the court ordered the entire Facebook site blocked.
Any representation of the Prophet Mohammad is deemed un-Islamic and blasphemous by Muslims.
By late afternoon, Facebook was unavailable to Pakistan's computer users, although Blackberries and other mobile devices appeared able to access the site.
But some warned the court's response could backfire.
Blocking the entire website would anger users, especially young adults, because the social networking website is so popular among them and they spend most of their time on it, said the CEO of Nayatel, Wahaj-us-Siraj.
Basically, our judges aren't technically sound. They have just ordered it, but it should have been done in a better way by just blocking a particular URL or link.
On the Facebook information page for the contest the organizers described it as a snarky response to Muslim bloggers who warned the creators of the Comedy Central television show South Park over a recent depiction of the Prophet in a bear suit.
We are not trying to slander the average Muslim, the Facebook page creators wrote. 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.
Publications of similar cartoons in Danish newspapers in 2005 sparked deadly protests in Muslim countries. Around 50 people were killed during protests in Muslim countries in 2006 over the cartoons, five of them in Pakistan.
Al Qaeda claimed responsibility for a suicide attack on Denmark's embassy in Islamabad in 2008, killing six people, saying it was in revenge for publication of caricatures.
Pakistan also blocked the popular video sharing site YouTube in 2007 for about a year for what it called un-Islamic videos.
(Additional reporting by Mubasher Bukhari in Lahore and Zeeshan Haider in Islamabad; Editing by Chris Allbritton)
(For more Reuters coverage of Afghanistan and Pakistan)