CAIRO, Egypt — Hundreds of democracy protesters denounced President Hosni Mubarak at a rally yesterday in Cairo while organizers said scores of activists were arrested in other cities.

The action by some 250 demonstrators — small by the standards of mass rallies in Lebanon or Bahrain — was a notable act of dissent in Egypt's strict political confines, extending a regional wave of democracy activities in recent months.

The rally drew intense scrutiny from authorities, who surrounded it with more than 1,000 helmeted riot police and plainclothes intelligence officers.

Leaders of the group, known by its slogan, "Enough!" or Kifaya in Arabic, had attempted to stage their largest public action yet, with coordinated protests in 15 cities from Aswan in the upper Nile valley to the Mediterranean city of Alexandria.

But authorities appeared to pre-empt that by rounding up at least 125 activists across the country, organizers said. All but two of those arrested had been released by last night.

Leaders in the capital could not be sure where other protests unfolded and where they did not. That would be a key indicator of whether Egypt's increasingly bold democracy movement has succeeded or failed in building strength beyond its core of urban intellectuals. Public protests against the government were all but unheard of in Egypt until late last year, when disparate opposition groups gelled into a movement that has successfully staged five rallies of 50 to 500 people.

At yesterday's four-hour rally, dominated by leftist and moderate Islamist intellectuals, protesters filled the steps of a journalists association, chanting slogans like "Let Mubarak fall." Standing among the uniformed security officials, men in plain clothes could be overhead talking into their cellphones, describing key protesters, identifying familiar faces and delivering word-by-word recitations of their chants.

The 76-year-old Mubarak has recently made gestures of political openness, calling for the country's first direct multiparty presidential elections. His regime has gingerly widened the window of acceptable dissent in the past two years, even though local and international-rights groups say it uses detention, beatings and harassment to pressure some political opponents.

Among their banners, demonstrators held posters expressing solidarity with Egyptian judges, who are threatening to boycott the elections if they are not given a measure of legal protection against interference by the security forces. Demonstrators said the effort to link their movement with the judges and other sources of opposition in Egypt will be a key factor in their potential impact.