Egyptian President Abdel Fattah al-Sisi has signed off on an anti-terrorism law that gives authorities more sweeping powers to ban groups on charges ranging from harming national unity to disrupting public order.

The move, announced in the official Gazette on Tuesday, is likely to increase concern among rights groups over the government clawing back freedoms gained after the 2011 uprising that ended a three-decade autocracy under Hosni Mubarak.

Authorities have cracked down hard on the Islamic groups, secular and liberal opposition alike since then army chief Sisi toppled elected president Mohamed Mursi in 2013 after mass protests against his rule.

According to the Gazette, the law enables authorities to act against any individual or group deemed a threat to national security, including people who disrupt public transportation, an apparent reference to protests.

Loose definitions involving threats to national unity may give the police, widely accused of abuses, a green light to crush dissent, human rights groups say.

The Interior Ministry says it investigates all allegations of wrongdoing and is committed to Egypt's democratic transition.

Under the mechanism of the law, public prosecutors ask a criminal court to list suspects as terrorists and start a trial.

Any group designated as terrorist would be dissolved, the law stipulates. It also allows for the freezing of assets belonging to the group, its members and financiers.

Since taking office in 2014, Sisi has identified Mursi's Muslim Brotherhood as a threat to national security.

He has linked the Brotherhood, the region's oldest Islamic grouping, with far more radical groups, including one based in Sinai that supports ISIL, allegations it denies.

Hundreds of supporters of the Brotherhood, which says it is a peaceful movement, have been killed and thousands arrested in one of the toughest security crackdowns in Egypt's history.

Some Egyptians have overlooked widespread allegations of human rights abuses and backed Sisi for delivering a degree of stability following years of political turmoil since 2011.

A court on Tuesday acquitted Mubarak-era prime minister Ahmed Nazif and former interior minister Habib el-Adly of graft charges, judicial sources said, a day after prominent activist, Alaa Abdel Fattah, was jailed for five years for violating limits on demonstrations.

"I served Egypt, and history will judge," Nazif told reporters at the court.