About 300 pro-reform judges staged a sit-in outside a downtown Cairo courthouse Thursday to demand the independence of Egypt's judiciary, under the watchful eyes of thousands of anti-riot police.

Scores of opposition activists organized separate protests in support of the judges, and to mark the first anniversary of a referendum on a constitutional amendment that allowed multicandidate presidential elections for the first time.

In one of the protests, an estimated 70 activists — from various groups including the pro-reform Kifaya movement, al-Ghad party and the outlawed Muslim Brotherhood — clapped and chanted anti-government slogans outside the headquarters of the Journalists' Union in downtown Cairo.

"Release our detained brothers," they chanted, referring to activists arrested in earlier demonstrations. Some participants clutched yellow stickers reading "Kifaya" or "Enough," while others plastered their clothes with green stickers reading "Long Live Justice."

"Oh, our great people. The hour of salvation is near," one banner read.

Earlier Thursday, an official said 41 students who had been detained during the street protests last week were released.

The students included members of the outlawed Muslim Brotherhood group and the anti-President Hosni Mubarak movement "Kifaya", or "enough", said the official on condition of anonymity because he is not authorized to speak to the media.

CountryWatch: Egypt

Riot police in helmets and shields packed several downtown streets around the courthouse and the union, but violence was on a much smaller scale than during protests the previous two weeks.

Plainclothes police beat and arrested two activists near the union's building, both of whom were only recently released after spending about one month in detention for taking part in a previous demonstration.

Up to 15 plainclothes security agents attacked one of the men, Mohammed el-Sharkawi, 24, and punched him to the ground before dragging him away.

Activists said another man, Kareem al-Sha'er, was leaving the Journalists' Union building in a private car when about 20 plainclothes officers stopped the car, smashed its windows and dragged him away. Another activist in the same car, Ahmed Salah, was beaten but not detained.

It was unclear if the security agents used weapons in the beatings.

The judges — who demand independence from Egypt's executive branch and unfettered supervision of parliamentary and presidential elections — wore green sashes and flashed V-for-victory signs in front of the courthouse.

In a similar protest in the southern province of Qena, police arrested a Kifaya member, Ashraf Abdel-Aziz, according to a colleague, Ahmed Taima. Taima said police beat some of the protesters there.

In the Sinai Peninsula town of el-Arish on the Mediterranean, about 100 protesters — including members of the leftist Tagammu opposition party and Kifaya — took to the streets in support of the judges and against the year-old constitutional amendment.

The referendum last year was marred by violence in which anti-government protesters and journalists, particularly women, were beaten, groped and sometimes stripped of their clothes allegedly by ruling National Democratic party supporters.

The amendment was criticized by opposition groups arguing that it made it virtually impossible for them to contest the presidential race.

Tagammu official Alaa el-Kashef was arrested during the el-Arish protest, according to Kifaya activist Ashraf Ayoub. Another Tagammu official, Ashraf el-Hefni, suffered bruises after police beat demonstrators, activists said.

Police were not immediately available for comment

The demands of the judges and protests in their support have become a rallying cause that reinvigorated Egypt's opposition groups. In the last two Thursdays, police arrested hundreds of protesters and beat others demonstrating in support of the two judges who have become symbols of the fight for reform when they blew the whistle on alleged fraud in last year's legislative elections.

Police treatment of the protesters this month drew criticism from the United States and the European Union and bolstered opposition charges that the government of President Hosni Mubarak, Egypt's ruler of nearly 25 years, was reneging on reform promises.