|Al Jazeera has won plaudits from around the world for its Egypt coverage
Al Jazeera has demanded that three of its journalists detained by Egyptian security forces be released immediately.
In a statement on Thursday, the network said another journalist covering the turmoil in the country has been reported missing.
"All three of our staff should be immediately released," the channel said. "We are concerned for their safety and welfare. We are taking every measure as a priority to obtain their release."
Though Al Jazeera's coverage of the Egyptian uprising has won plaudits from around the world, with its journalists reporting from the heart of the events in the capital Cairo and elsewhere, it has faced constant hindrances within the country.
Al Jazeera had six journalists detained by authorities for several hours in the past week, with equipment stolen and destroyed. It has also faced unprecedented levels interference in its broadcast signal across the Arab world.
On Thursday, Omar Suleiman, the newly appointed vice-president, told Egyptian state TV that a "satellite channel based in a friendly country" was exaggerating the events and showing Egypt in a bad light. However, he did not name the channel.
Journalists have found themselves in the line of fire amid the turmoil in Cairo with many being beaten up by loyalists of Hosni Mubarak, the Egyptian president.
Al Jazeera's online producer, reporting from Tahrir (Liberation) Square, said journalists in Egypt - domestic and foreign - are increasingly under siege.
"Egyptian authorities [are] detaining reporters and gangs of young men [are] roaming the streets looking for anyone with camera equipment," according to our producer.
"Spotters stand outside many hotels, watching balconies with high-powered binoculars. When they see balconies with camera equipment or photographers, they use radios to call in the details.
"Egyptian police sources say that information from those spotters has been used to conduct several raids on journalists' hotel rooms in recent days. And the government has reportedly pressured several hotels not to extend the reservations of foreign journalists."
The United States has condemned a "concerted campaign" to intimidate foreign journalists covering the Egyptian protests.
Robert Gibbs, White House spokesman, called for the release of any journalist who had been detained in the country and said acts to intimidate the media were "completely and totally unacceptable".
Britain's foreign minister echoed concerns, saying the intimidation and harassment of journalists were "unacceptable and disturbing".
The New York-based Committee to Protect Journalists called the attacks on journalists an attempt at "blanket censorship" by the government, and listed a number of reported assaults against Egyptian, Arabic and international media.
Source: Al Jazeera