A court in Pakistan has ordered the authorities temporarily to block the Facebook social networking site.
The order came when a petition was filed after the site held a competition featuring caricatures of the Prophet Muhammad.
The petition, filed by a lawyers' group called the Islamic Lawyers' Movement, said the contest was "blasphemous".
A message on the competition's information page said it was not "trying to slander the average Muslim".
"We simply want to show the extremists that threaten to harm people because of their Muhammad depictions that we're not afraid of them," a statement on the "Everybody Draw Muhammed Day" said.
"They can't take away our right to freedom of speech by trying to scare us into silence."
The page in question contains caricatures of the Prophet Muhammad and characters from other religions, including Hinduism and Christianity, as well as comments both critical and supportive of Islam.
Publications of similar cartoons in Danish newspapers in 2005 sparked angry protests in Muslim countries - five people were killed in Pakistan.
Already the Pakistani press has reported protests against Facebook on Wednesday by journalists outside parliament in Islamabad, while various Islamic parties are also reported to be organising demonstrations.
Correspondents say that the internet is uncensored in Pakistan but the government monitors content by routing all traffic through a central exchange.
Justice Ejaz Ahmed Chaudhry of the Lahore High Court ordered the department of communications to block the website until 31 May, and to submit a written reply to the petition by that date.
An official told the court that parts of the website that were holding the competition had been blocked, reports the BBC Urdu service's Abdul Haq in Lahore.
But the petitioner said a partial blockade of a website was not possible and that the entire link had to be blocked.
The lawyers' group says Pakistan is an Islamic country and its laws do not allow activities that are "un-Islamic" or "blasphemous".
The judge also directed Pakistan's foreign ministry to raise the issue at international level.
In the past, Pakistan has often blocked access to pornographic sites and sites with anti-Islamic content.
It has deemed such material as offensive to the political and security establishment of the country, says the BBC's M Ilyas Khan in Islamabad.
In 2007, the government banned the YouTube site, allegedly to block material offensive to the government of Pervez Musharraf.
The action led to widespread disruption of access to the site for several hours. The ban was later lifted.
Read a selection of comments from Pakistan:
I don't think that the court has made the right decision. Now searching on Facebook, I don't see any such group! I am not sure if the court was given the true story with proper proof, or if so, it should be made public too! Having said that, Facebook admins should make sure that such anti-Muslim zealots who plan to provoke such agitation should be banned and such utterly bizarre stuff shouldn't even taken place in the name of any competition! It's ridiculous.
I am a regular user of Facebook. The court has made the right decision. If this thing continues, the authorities should ban Facebook permanently. This is the first time after 9/11 that any institution in Pakistan has given a kind hearing to the voice of the public. Further, if these actions persist, the government should end friendly and diplomatic ties with any country that supports blasphemous acts like this.
Asad Fareed, Rawalpindi
No. It is a wrong decision. Ban does not do anything. Are you going to ban eveything on the internet that inflames someone's sensibilities? Stupid! If someone is inflamed and feels hurt, then do not go to that website.
Aurangzeb Haneef, Karachi
Yes, I do use Facebook regulary. The court has certainly made the right decision and we strongly support it. People should respect each other's beliefs and exhibit tolerance. We, as muslims, hold nothing dearer than our Holy Prophet and such a disrespectful, blasphemous act would not be ignored or tolerated!
Rabia Liaqut, Lahore
I feel that the court should not have blocked facebook and instead let Pakistani muslims use the website as a forum to protest what they felt was wrong and blasphemous. However, I do believe that Facebook should monitor content published on the website and control the formation of potentially volatile groups that could be offensive to certain religions. It is a commonly known fact that muslims feel strongly about pictorial depictions of prophet Mohammad and Allah (God) and, therefore, people should be respectful of that instead of trying to irk muslims and create controversies just to prove that 'muslims' in general are a fundamentalist and unreasonable people who do not believe in freedom of speech.
It's great action. Many Pakistanies have already left the site. We are happy because we love our Prophet Muhammad more than Facebook.
Aqeel Shuja, Sialkot