Egypt's pro-reform movement Kefaya (Enough) gained considerable ground when it staged simultaneous rallies across the country in protest at President Hosni Mubarak's unchallenged 24-year-old rule.
Defying a ban against street demonstrations, the coalition group of Marxists, Nasserites, liberals and Islamic dissidents from the Muslim Brotherhood coordinated 14 marches Wednesday at the same time under the banner "no constitution without freedom."
Kefaya, which first surfaced in December, has been profiting from a growing wave of dissent recently joined by university students, judges and teachers - all urging overdue democratic changes.
Demonstrators have been increasingly bold in their calls to lift the state of emergency imposed after the assassination of Mubarak's predecessor, Anwar Sadat, 24 years ago.
Kefaya has even dared to publicly ask Mubarak to step down.
"Enough", "No to a fifth mandate", "No to Mubarak, his party and his son", "Mubarak you failed us, what did you do with our money?", "Mubarak, American agent", are slogans often heard at Kefaya's rallies.
Under growing domestic and international pressure, Mubarak proposed an amendment to the constitution in February allowing for unprecedented multi-candidate elections, although the reform is expected to remain limited.
Opposition elements insist that the amendment should also limit the number of consecutive presidential terms to two instead of open-ended repetitions.
The 76-year-old veteran leader has not yet announced whether he intends to seek a fifth six-year mandate next September.
In a statement posted on the Internet Wednesday, Kefaya said it had called for demonstrations that are "peaceful and silent and in favor of rapid changes."
Attacking the constitutional amendment, "arbitrary" measures and pervasive corruption, it said "the freedom of the Egyptian people demands the end of the (current) regime and its policies and personalities"
The group underscored "the need for a new constitution, drafted by a constituent and freely elected assembly", asked for "the freedom to form political parties and publish papers" and called for a "clean hands campaign".
Some 75 protestors around the country were arrested but later released, the organization chief, George Isaac, said, in the single largest number of arrests since opposition elements escalated their campaign against Mubarak.
In Cairo, hundreds of riot police sealed off roads leading to the supreme court compound where Kefaya had planned to stage a rally and beat with batons those who tried to make their way to the building.
Some 300 Kefaya activists later managed to get through and gathered in front of the nearby Journalists' Union headquarters.
They chanted anti-Mubarak slogans before dispersing.
In the eastern city of Suez, police "attacked demonstrators and confiscated their banners", Kefaya said, saying that 20 had been arrested.
In the Mediterranean port of Alexandria, security forces contained and dispersed demonstrators who attempted to gather around the city's criminal court.
Meanwhile, police in the north Sinai town of El-Arish cornered dozens of demonstrators who continued to chant anti-Mubarak and pro-reform slogans. Ten people were detained, but five of them were released shortly after.
Two people were also arrested in the southern town of Minya, while 10 others were detained in Mansurah, north of Cairo.