Foreign photographers reported attacks by supporters of President Hosni Mubarak near Tahrir Square, the scene of vicious battles between Mubarak supporters and protesters demanding he step down after nearly 30 years in power. The Egyptian government has accused media outlets of being sympathetic to protesters who want Mubarak to quit now rather than complete his term as he has pledged.
Among the many detained were correspondents for The New York Times, Washington Post and Al-Jazeera.
"This is a dark day for Egypt and a dark day for journalism," said Joel Simon, executive director of the Committee to Protect Journalists. "Egypt is seeking to create an information vacuum that puts it in the company of the world's worst oppressors."
Human rights organizations also were targeted. Some of the groups said many activists were taken away after a raid by the military police on a legal center in Cairo.
In Berlin, U.N. Secretary-General Ban Ki-moon condemned the "intimidation and restrictions" being placed on journalists and human rights groups in Cairo.
"Let me absolutely clear: this is outrageous and totally unacceptable," he said after meeting Germany's president, Christian Wulff. "It must stop now."
CPJ said some state-owned television outlets and private stations owned by businessmen loyal to Mubarak had been portraying journalists as part of plots to destabilize Egypt.
BBC foreign editor Jon Williams said via Twitter that security forces seized the network's equipment in a Cairo Hilton hotel in an attempt to stop it broadcasting. Many international news organizations have been using the Ramses Hilton overlooking Tahrir Square as a base to cover the mayhem.
Unidentified men entered the Cairo office of the U.S.-funded Alhurra television and threatened to kill the station's two on-air journalists, the station's governing board said. The station was closed and bureau activities relocated.
Two Fox News Channel journalists were severely beaten by a mob near Tahrir Square on Wednesday. Correspondent Greg Palkot and cameraman Olaf Wiig had retreated to a building, but someone threw a firebomb inside and the men were attacked as they rushed out, said Michael Clemente, Fox's senior vice president for news.
Palkot and Wiig escaped to a hospital with the help of anti-Mubarak demonstrators, Clemente said. Palkot hasn't been on the air and, for safety reasons, Fox held off for a day in reporting about its personnel.
Swedish public broadcaster SVT said one of its reporters, Bert Sundstrom, was stabbed Thursday. The network said it's unclear what happened but that when an editor called Sundstrom's cell phone a man answered in Arabic that the reporter was in the hands of the Egyptian government. SVT said Sundstrom was seriously injured but described his condition as stable.
White House spokesman Robert Gibbs denounced reports of "systematic targeting" of journalists in Egypt. The State Department described it as a "concerted campaign to intimidate."
"I think we need to be clear that the world is watching the actions that are taking place right now in Egypt," Gibbs said.
The Sunday Times newspaper's foreign affairs correspondent, Marie Colvin, said armed men gathered outside a home where she was interviewing the family of a protester who'd been shot.
The men of the family locked her in a nearby shop and then helped her through the shoving, shouting crowd to a car, she said.
"What happened today was terrifying," Colvin said. "And you can't call the police."
Douglas Jehl, foreign editor for The Washington Post, said on the paper's website that Cairo bureau chief Leila Fadel and photographer Linda Davidson were held by military police and released. Their translator, Sufian Taha, and driver, Mansour el-Sayed Mohammed Abo Gouda, were believed to remain in custody, Jehl wrote.
Pan-Arab broadcaster Al-Jazeera said three of its journalists were detained by security forces and another was missing.
Egyptian authorities have complained the network's coverage was slanted in favor of protesters and could encourage unrest.
Al-Jazeera also said equipment was stolen and destroyed during the 10 days of protests and its broadcast signal was disrupted across the Arab world.
The Arabic-language satellite channel Al-Arabiya pleaded on an urgent news scroll for the army to protect its offices and journalists.
Two Japanese freelance photographers were attacked while covering the protests, and one of them was slightly injured, the Kyodo News agency reported. It was not clear whether they were assaulted by pro- or anti-Mubarak protesters.
The Paris-based all-news channel France 24 said three of its journalists had been detained for 24 hours, then freed for several hours, then detained again.
The Toronto Globe and Mail said two of its reporters were detained by the military for about three hours. One, Sonia Verma, said the pair was picked up with about 25 other foreigners, including other journalists.
The Greek daily newspaper Kathimerini said its correspondent in Cairo was briefly hospitalized with a stab wound to the leg after being attacked by pro-Mubarak demonstrators in Tahrir Square. A Greek newspaper photographer was punched in the face.
The injured Greek correspondent, Petros Papaconstantinou, said on Kathimerini's website that: "I was spotted by Mubarak supporters. They ... beat me with batons on the head and stabbed me lightly in the leg. Some soldiers intervened, but Mubarak's supporters took everything I had on me in front of the soldiers."
The leaders of France, Germany, Britain, Italy and Spain said in a joint statement that the "attacks against journalists are completely unacceptable."
Associated Press spokesman Paul Colford said that "AP journalists in Egypt have faced the same harassment and intimidation as other news organizations."
One Associated Press location was disrupted by men wielding sticks, and satellite equipment was taken.
"The situation was quickly defused," Colford said. "No one was injured."
Other news outlets reporting beatings and detentions include Turkey's state broadcaster TRT, whose Egypt correspondent, Metin Turan, lost a tooth after being beaten by pro-Mubarak demonstrators with batons. His camera, money and cell phone were stolen.
Polish state television TVP said that two of its crews were detained in Cairo. One was released after one of its cameras was smashed, it said.
Government spokesman Magdy Rady on Wednesday denied government involvement in attacks on reporters and said officials welcomed objective coverage.
"It would help our purpose to have it as transparent as possible. We need your help," Rady told The Associated Press. However, he said some media were not impartial and were "taking sides against Egypt."
CNN's Anderson Cooper said he, a producer and camera operator were set upon by people who began punching them and trying to break their camera on Wednesday.
In Wednesday's fighting, security forces did not intervene as thousands of people hurled stones and firebombs at each other for hours in and around Tahrir Square.
Jean-Francois Lepine of Canada's CBC all-French RDI network said that he and a cameraman were surrounded by a mob and were rescued by the Egyptian army.
"Without them, we probably would have been beaten to death," he said.
Associated Press journalists around the world contributed to this report.