By Edmund Blair
CAIRO (Reuters) - Egyptians gathered in Cairo's Tahrir Square on Friday, after a week of demonstrations, to tell the ruling generals they are failing to meet demands to reform the system.
But the Muslim Brotherhood, Egypt's most organized group, said it was not participating and said the authorities must have time to respond to demands first made at a mass rally last week.
The split partly reflects caution in the Brotherhood, banned under ousted President Hosni Mubarak, about riling the army under which it now has unprecedented freedom.
Analysts said it also indicates the gap between the Brotherhood's cautious approach and a new generation of activists, who are less well established but determined to keep up the pressure.
"The youth reject the language of threats used by the Supreme Council (for the Armed Forces), and reject that this is the way for dialogue," said Mohamed Adel of the April 6 movement, which has been calling for a big turnout on Friday.
Hundreds of demonstrators gathered in Cairo and Alexandria on Friday by noon prayers. Numbers tend to climb after prayers, when the summer heat cools in the afternoon and evening.
Activists, some of whom have camped in the square for a week sheltering under canopies from the scorching sun, were angered by the tone of an army statement this week that suggested protests were threatening public order.
At a news conference, generals defended the use of military courts saying they had not been used to stifle opinion but only against serious crimes. The army also said it would use all legal means to end the protest without resorting to violence.
But there has been no sign of any action to stop the protest in Cairo or in other cities where demonstrators have rallied.
The army has also said it backed the prime minister, Essam Sharaf, who is working on a cabinet reshuffle. Other concessions include a shake up of hundreds of senior officers in the police, a force scorned for violent tactics used under Mubarak.
"Purging all state institutions and particularly the judiciary," is one of the demands listed by April 6.
The movement and others have named officials still in place that it wants fired. They have also demanded that military courts, long used by Mubarak, should not be used for civilians.
Among the demonstrators is Muhammed Fawzy, who said he began a hunger strike in Tahrir on July 10 and only drinks water. He wants a dialogue with the army about his demands, such as setting up an independent committee to draw up a constitution.
The Brotherhood said it would stay away. The group is widely seen to have benefited most from the army's policies, such as the military's drive for a swift election, although voting has been pushed back to November from September.
"We will not participate today. That does not mean that we are against demonstrating or against continuing the revolution strongly. But we ... participated last Friday in big numbers and with specific demands and we say we must give a chance in each period for our demands to be met," Mohamed Morsy, head of the Brotherhood's political Freedom and Justice party, told Reuters.
"If they are not met enough we will return again to the square, and not just there, but to all squares," he said, adding that the group did not oppose others demonstrating.
The Brotherhood, though banned under Mubarak, was given enough room to build a broad network of support through social and charity work. It also ran candidates as independents in parliament elections, winning 20 percent of seats in 2005.
Hassan Nafaa, a political scientist and activist, said the Brotherhood might be wary of antagonizing the military council when the group now has more freedom to act than any time before.
"It is good for others to prove they can mobilize, act and have initiative without the Muslim Brotherhood," he said.
Nafaa said the army may had tended to side with Islamists believing it was the best way to control the streets, adding: "The military council should understand now that the Muslim Brotherhood and Islamist trend is not the whole scene."
(Editing by Jon Hemming)