Egyptian activist Sanaa Seif surrendered herself to the prosecution on Saturday, in order to serve a six-month sentence she was given this month for “insulting the judiciary.”

Although the sentence can still be appealed, the well-known activist said she wouldn’t challenge the ruling as she no longer has confidence in the judicial system.

In April the prosecution referred Seif, who comes from a family of well-known human rights activists and lawyers, to court after she refused to cooperate with their investigations.

She was being investigated on charges of inciting protests in April against the Egyptian government's announcement that it would recognise two islands in the Red Sea as belonging to Saudi Arabia, and of distributing posters to citizens in the Moqattam area of Cairo.

Seif described the investigations as a “farce” in comments reported by her sister Mona Seif on her Facebook page; the prosecution considered the comment an insult to the investigators.

The 21-year-old is the daughter of late human rights lawyer Ahmed Seif El-Islam; her sister is also a human rights activist, and her brother is blogger Alaa Abdel-Fattah, who is serving a jail sentence for protesting illegally.

She was among a group of activists arrested at a protest march in June 2014 that called for the repeal of the 2013 law which bans demonstrations without police authorisation and punishes violators with imprisonment.

She was sentenced to three years in prison, and received a presidential pardon in September 2015 after having served 15 months.