Ten activists who were arrested late on Thursday in Cairo in connection with planned protests next week were released on Friday, while dozens of others remain in custody under investigation, according to the "Freedom for the Brave" campaign.

Police raided several Cairo cafes as well as private houses in Alexandria, the Nile Delta and Upper Egypt on Thursday night and arrested dozens of people ahead of planned protests on 25 April.

Earlier on Friday, rights lawyer Amr Emam told Ahram Online that at least 100 people were estimated to have been arrested around the country on Thursday night. 

Emam said that in Cairo at least 56 people were arrested and in other governorates authorities raided houses and arrested some 45 people.

Among those who remain in custody are activists Haitham Mohamadein and Mohamed Mostafa.

Last week, several thousand protestors took to streets to oppose the government’s decision to acknowledge Saudi Arabian sovereignty over the Red Sea islands of Tiran and Sanafir. They had vowed to stage another protest on 25 April, which is Sinai Liberation Day.