"Down with military rule," demonstrators shout in downtown Cairo as they march from the opera house to the journalists' union building. But it's a rare sight - since a new law on demonstrations was passed in November last year, few have dared to shout such slogans.

The law says that all demonstrations need to be approved by the interior ministry - effectively banning them, the opposition says. Violations of the law can be punished with prison.

Opposition leaders are calling their protest a "marathon," even if the march is less than two kilometers.

Demands to release political prisoners

Around 300 participants clap their hands and shout slogans against the military. They also demand the release of political prisoners.

Last week an appeal court confirmed the sentences of activists Ahmad Douma, Ahmad Maher and Mohamed Adel. For many, the last straw. The three activists were sentenced to three years in prison and a 5,000 euro fine for violating the new law.

"Revolutionaries are not criminals," shouts 60-year old Oum Ali. She covers her head in a dark blue scarf and wears a black robe and glasses. The current regime is no better than that of authoritarian President Hosni Mubarak, she says.

"The demonstration law brings Egypt back to the times before the revolution," Oum Ali shouts into a microphone. "The youth of the revolution is imprisoned."

Oum Ali is angry with the interim government and Abdel-Fattah el-Sissi, presidential candidate and former army chief: "We brought the current government to power by demonstrating against the Muslim Brotherhood on June 30, 2013. How is it possible that they can now prohibit demonstrating for our demands?"

The current regime draws its legitimacy from last summer's protests against the Brotherhood. It now describes the way it took power as a revolution. Only a few regime critics call the military takeover a coup - and they face arrest for using the word.

'Two sides of one coin'

That has led to international criticism of the military regime. Rights watchdog Human Rights Watch demanded in a letter to US Foreign Minister John Kerry that the US halt all military aid to Egypt. It says more than 1,000 demonstrators have been killed and 16,000 arrested since the military came to power.

Most of the arrested have been accused to be members of the now-outlawed Brotherhood. But there have also been cases in which Christians were arrested on the same charges. People have also been tried twice, once for taking part in demonstrations against the Brotherhood and a second time for membership in the Brotherhood.

This arbitrariness makes the marchers even angrier. By now they have reached the musicians' union headquarters. They carry pictures of political prisoners and banners denouncing the demonstration law. They feel betrayed by the military, which they say is ignoring the demands of the 2011 revolution that deposed Mubarak, and is acting in the same way his government did.

Oum Ali took part in the demonstrations in 2011 and says she does not notice any improvement. She says that Egypt is far away from the revolution's goals: freedom, social justice and human dignity for all citizens. "Unfortunately we have been set back three years. We sacrificed the blood of our children," she said.

"We overthrew Mohamed Mursi because he wanted to restrict or freedom. And then Sissi's regime came to power. He restricts our freedom even more and uses the Brotherhood as a scapegoat. The Brotherhood and the military are two sides of the same coin!"

More protests announced

The marathon was just the first step, says Mervat Moussa, who took part. She describes herself as "a normal Egyptian woman."

"We want the abolition of the demonstration law," she says, adding that the law was only implemented to silence the activists.

"These people were arrested under the emergency law and then sentenced under the penal law," Moussa said. "In this way the government is trying to save its image. If you ask about repression, the government can say it doesn't have any political prisoners." She is convinced that the trials were politically motivated.

That's why the demonstrators want to continue. "There will be new activities every day," Moussa said. She provided no further details - the only way to make sure that the security forces won't attack her and that the protests remain peaceful.

"There are enough people who want to use these activities for their own aims," she said. "We are not the Muslim Brotherhood and we don't belong to any party. We have been independent from the first day of the revolution until today. We will protest as long as there is injustice in Egypt."

Ahmad Douma, Ahmad Maher and Mohamad Adel, the three imprisoned activists, have already announced that they will go on hunger strike, saying they want to complete the democratization process and meet the revolution's goals.

The government says one of these goals is the presidential elections on May 25 and 26. The former army chief is expected to win.