CAIRO, Egypt - More than 3,000 Egyptians marched through downtown Cairo on Monday, protesting the military's arrest of a prominent blogger-activist in the latest sign of discontent with the ruling generals' managing of the country.

The activist, Alaa Abdel-Fattah, was ordered held by the military a day earlier for questioning. The military says he is suspected of inciting Christian protesters to attack soldiers during an Oct. 9 protest in Cairo that turned into the bloodiest violence since the February fall of President Hosni Mubarak.

His supporters dismiss the claim, saying the military is trying to silence a prominent critic and to deflect blame on its soldiers in the violence, which left 27 dead -- most of them Christians -- when troops cracked down on the protest.

In Monday evening's march, the crowd shouted, "Down, down with military rule" and "Alaa, we're behind you, don't stop," as they moved into central Tahrir Square, then headed toward Cairo's main police station, where Abdel-Fattah is being held.

About 200 police formed a line around the station. There were no clashes.

Abdel-Fattah, who turns 30 in November, was Egypt's first blogger activist, launching a blog years ago organizing opposition to Mubarak. Since Mubarak's Feb. 11 ouster following an 18-day uprising, he has been a vocal critic of the military's rule.

"Alaa is causing them trouble because he's been an activist for so long. He has many people around him he can influence. They don't want this voice now," said one 24-year-old protester, Andy Ishaq, referring to the military leadership. Like others in the march, he wore a yellow sticker reading "I am against military trials for civilians."

Egyptians have been growing increasingly discontented with the ruling generals, who have been criticized for mismanaging the economy and preparations for upcoming parliamentary elections and for increasingly using the same heavy-handed methods as Mubarak's autocratic regime. Thousands of civilians have been put on military trials -- including some protesters and activists.

The bloodshed at the Oct. 9 Christian protest was a heavy blow to the military's prestige. Videos showed soldiers shooting toward protesters and mowing them down with armoured vehicles. The military tried to exonerate itself, denying its troops shot protesters or intentionally ran them over and blaming the Christians and "hidden hands" for starting the violence -- though witnesses said the soldiers were the first to attack.

Abdel-Fattah was brought in for questioning on Sunday. He refused to respond to questions, saying he does not recognize the military's right to investigate violence that it is accused in.

Abdel-Fattah's wife, who is about to give birth to their first child, was among the marchers.

"We're trying to keep the focus on military trials of civilians, not just on Alaa," Manal Hassan said, adding that they plan to name their firstborn Khaled after Khaled Said, the young man from Alexandria whose death while in police custody helped spark the uprising against Mubarak.

The Committee to Protect Journalists called it "the height of hypocrisy" for the ruling military council to try to intimidate critics through military trials after claiming to support the uprising. The group called for Abdel-Fattah's immediate release. "Failure to do so belies claims that authorities have broken from the intimidation tactics of the past 30 years," said CPJ's Middle East co-ordinator, Mohamed Abdel Dayem.

Amnesty International on Monday also criticized the trials of civilians in military courts, as well as the military's expansion of Egypt's emergency law, which gives police almost unlimited powers of arrest. The law was widely hated in Egypt, and its lifting was a top demand of the protesters who brought down Mubarak.

In the latest trial, a military court on Monday gave six-month suspended sentences to 73 people for their involvement in a September attack that damaged an office of the Israeli Embassy in Cairo, prompting the ambassador and his family to temporarily leave the country.

Egyptian soldiers and police watched impassively as crowds tore down a security wall, stormed the high-rise apartment building, climbed to the embassy and trapped six Israeli guards while throwing Hebrew documents out the windows. Three people died in and more than 1,000 were injured in the Sept. 9 violence when police finally cracked down on the rioters.

The 73 defendants were convicted with using force against officials, destruction of public property and breaching public security.

Also Monday, the Egyptian flag was hoisted on a new 575-foot (176-meter) iron tower in Cairo as part of the 38th anniversary of Egypt's 1973 war against Israel -- and it coincided with military ruler Field Marshal Hussein Tantawi's 76th birthday.