Black-clad Egyptian police descended on two small anti-government rallies in Cairo on Tuesday and fired water cannons to disperse them, enforcing a controversial new law restricting protests. The heavy hand fueled a backlash among secular activists and liberals who accuse the military-backed government of accelerating down a path even more authoritarian than the Hosni Mubarak era.

The scenes of protesters being dragged away and beaten, with dozens arrested, pitted security forces against secular youth activists, in a new front after months of a heavy -- and far bloodier -- crackdown on Islamists since the army's ouster of President Mohammed Morsi. Criticism came even from supporters of the new military-backed government, who warned that the new law will increase opposition and could push secular activists into a common cause with Islamists.

The criticism presents a sharp challenge to the government: It threatens to break the loose coalition of secular and liberal politicians and revolutionary activists who gave key legitimacy to the military's July 3 ouster of Morsi, Egypt's first freely elected president.

That coalition argued that the military's move, following massive anti-Morsi protests, was necessary for a democratic, secular Egypt, accusing Morsi's Muslim Brotherhood of subverting the hopes for change after Mubarak's fall in 2011. Its factions backed the military and government -- or at least remained silent -- when security forces in August crushed pro-Morsi protest camps in a brutal crackdown that killed hundreds.

Now discontent is growing, particularly among young secular activists who led the anti-Mubarak uprising and are already mistrustful of the military.

Many are further angered by the process of amending the Morsi-era constitution, largely done behind closed doors, because it is likely to ensure greater powers for the military and the president. They believe the protest law aims to prevent criticism of the new document, due to be put to a public referendum in January. A day earlier, the powerful military chief Gen. Abdel-Fattah el-Sissi said in a speech to officers that political factions should stop pushing unrealistic demands and get in line behind the need to bring security in the country.

Manal el-Tibi, a member of the state National Council for Human Rights, said that the interim government is creating "more enemies" and the law will only increase protests.

"This has driven a wedge in the alliance" formed against Morsi, she said. "This is too much too soon."  The government claimed it took on recommendations from the rights council about the law, but el-Tibi said the body had urged authorities not to release it.

To protest the crackdown, 10 members suspended their participation in the 50-member, government-appointed panel amending the constitution, saying they would not return until activists jailed Tuesday are freed. One of the day's rallies took place outside the parliament building where the panel was meeting, forcing it to adjourn for the day.

"The victim will be the panel and its work, and the ultimately the country," said Diaa Rashwan, the head of the journalist union and a member of the panel. "We object to the way the Interior Ministry has treated the protesters."

The government says the law is needed to restore security and rein in near daily protests by Morsi supporters demanding his reinstatement. The Islamist rallies have often descended into bloody clashes with security forces, leaving hundreds dead. The government's message has a strong resonance among a public weary of constant protests and unrest.

But critics say the law silences all dissent -- effectively banning the sort of protests that ousted Mubarak and led to the removal of Morsi. It requires would-be protesters to get a permit for any gathering of more than 10 people days in advance from security officials, who can reject applications for a number of vague reasons. It imposes stiff fines and prison sentences on violators.

Maj. Gen. Abdel-Fattah Othman, a police spokesman, warned challenges to the law would not be tolerated, announcing the break-up of Tuesday's protests.

"This behavior is a challenge to the state and its prestige. The protesters want to embarrass the state," he said on the private CBC TV channel. "But the state is capable...Any gathering without a permit will be dealt with according to the law."

Though there was no bloodshed, the scenes Tuesday recalled Mubarak-era crackdowns, when police would move fiercely to suppress even the smallest protests.

Each of Tuesday's rallies numbered about 100 people. The first was held in downtown Cairo to commemorate an activist -- Gaber Salah, known by the nickname "Gika" -- killed by police a year ago. Police quickly deployed and warned the group to disperse because it had no permit.

When the protesters refused, the police opened up with water cannons, sending them running into side streets, said Rasha Azab, an activist at both of the day's protests.

Hours later, a similar group sprung up outside parliament, protesting an article in the constitution allowing military trials of civilians. "Down with military rule," they chanted. Again, police gave a warning, then fired water cannons. At least 48 were arrested, including Mona Seif, who leads the anti-military trial movement, and others of the country's most prominent youth activists.

"They don't want anyone in the streets any more. Not us, not the Islamists," Azab told The Associated Press before she was detained in the second protest. "They want to bring us back" to before 2011.

She and other activists say the military and security forces see the secular activists -- with their demands for democratic reform -- as a greater threat than the Brotherhood, which has been crippled by the crackdown of past months.

On Tuesday, Islamists stayed largely out of the fray. They held small rallies that were not broken up by security forces.

Ghada Shahbendar, a rights activist whose daughter was also among those detained, said girls had complained they were sexually harassed by police in detention, while others were beaten. Shahbendar said the timing of the law is "dubious" ahead of an election season, reflecting activist worries of a crackdown on dissent ahead of not only the constitutional referendum but also parliamentary and presidential elections due to follow.

The police "don't learn from (previous) lessons. The police state holds learning in contempt. They are bullish, arrogant. All they are for is oppressing people."

Another prominent liberal politician, Ehab el-Kharrat, of the Egyptian Social Democratic Party which is highly represented in the government, blasted the law and urged the interim president to reconsider it.

Speaking on CBC, he said that under Morsi, the Brotherhood had mistakenly dismissed liberals as insignificant. "Now whoever thinks that the people will welcome repression will very soon discover their mistake."

International criticism of the protest law has also grown.

U.S. State Department spokeswoman Jen Psaki said Tuesday that the law raises concerns. "We urge the interim government to respect individual rights and we urge that the new constitution protect such rights," she said.

Amnesty International and Human Rights Watch also deplored the new law.

HRW's deputy Middle East director, Joe Stork, warned the law would have "a further chilling effect" on the upcoming series of elections.