Egyptian security forces fired teargas Wednesday afternoon at protesters in Alexandria, defying a new law that curbs demonstrations, as authorities continue to quell street movements that officials say are unauthorised.

Clashes erupted between police and a group of activists protesting against the recently-issued legislation and police practices around a court complex in the centre of the Mediterranean city, state news agency MENA reported.

Police fired rounds of teargas at stone-hurling protesters and attempted to arrest many of the participating activists, MENA added.

The new contentious protest law mandates the approval of the authorities for demonstrations three-days beforehand, and gives the Interior Ministry discretion to forbid gatherings of ten or more individuals.

Interim authorities have been criticised by political and human rights groups since the law was signed by interim president Adly Mansour last Sunday. Anger simmered when police began to implement the new law, using water cannons and teargas to scatter peaceful demonstrations in downtown Cairo on Tuesday.

Police arrested dozens of protesters as they broke up demonstrations by youth groups and activists against the law.

Some 28 protesters were released Tuesday evening, but 24 activists were detained for four days pending investigation into allegations of rioting, carrying weapons, disrupting public interests, exposing people to danger, blocking roads, assaulting an employee during work, theft and thuggery, judicial sources told Ahram Online.

Meanwhile in another area of the city, a misdemeanour court held the second hearing in the trial of 22 Islamist women related to clashes during a protest supporting toppled Islamist president Mohamed Morsi. Defendants in the case include seven underage girls, judicial officials said. Others are reportedly in their twenties. The trial began last Wednesday.

Egypt's interim authorities have mounted a fierce crackdown on Morsi-supporters following his 3 July overthrow by the military amid mass protests against his turbulent one-year reign.

More than 1,000 people have been killed in clashes since Morsi's exit, and thousands of Islamists have been detained, including Morsi himself, who is currently facing charges of incitement to murder protesters during his presidency.

Although the battle against Islamist insurgency has presented the pretext for the new law, it mandates tough measures against all non-approved demonstrations.

However, the government has stressed it is not opposed to peaceful protests, but rather seeks to restore order in a nation reeling from political turmoil and street violence.