CAIRO : Egyptian police used water cannon on Tuesday to disperse the first unauthorised protest staged in Cairo since the adoption of a law that regulates demonstrations.

Protesters were demanding the prosecution of those responsible for the deaths of demonstrators in November 2011 when opponents of the then military junta clashed with police in the capital.

On Sunday, interim president Adly Mansour passed a law that allows security forces to gradually step up force while dispersing protests.

It allows security forces to first issue verbal warnings to protesters, then use water cannon, tear gas and, finally, birdshot while breaking up demonstrations.

The law also stipulates that protest organisers have to give three days’ notice before holding any demonstrations.

“The law must be repealed,” said Ahmed Maher, founder of the April 6 movement that spearheaded the 2011 revolt that toppled former autocratic president Hosni Mubarak.

“The interior ministry does not want any protests,” he said, adding that “even under Mubarak we could hold protests”.

Amnesty International said the law was a “serious setback that poses a grave threat to freedom of assembly and gives security forces a free rein to use excessive force, including lethal, against demonstrators”.

The Islamist Freedom and Justice Party, the political arm of the banned Muslim Brotherhood, also condemned the law.

It said that “instead of stopping the security forces’ repressive and murderous practices, (the law) entrenches brutality and abuse”.

Egypt’s military-installed authorities are engaged in a brutal crackdown since August 14 on Islamist supporters of ousted president Mohamed Morsi, the country’s first democratically elected leader.

He was overthrown on July 3 after mass street protests against his turbulent single year of rule.

Since then, more than 1,000 pro-Morsi protesters have been killed and thousands more arrested.