CAIRO, Jan 27 (Aswat Masriya) – The Egyptian Center for Social and Economic Rights (ECESR) said its lawyers are filing a complaint to Egypt's top prosecutor to detail the "extreme violations" surrounding an investigation with 79 people.

The investigation, which started on Tuesday afternoon, is still ongoing inside a central security forces camp, said lawyer Amr Hassan from the Association of Freedom of Thought and Expression, another NGO assisting in the investigation.  

Hassan said holding an investigation in a security forces camp is "not legal", adding that the camp is an illegal place of detention.  

Initially only 10 lawyers were allowed to attend the investigation. However, Hassan said that after negotiations, a total of 25 lawyers were eventually allowed access to the investigation but seven remained outside.     

ECESR said the 79 had been "missing" prior to the investigation. Hassan said this is because the group was arrested on Sunday but there was no information about them at the prosecution or any records of their arrest until late on Monday.

He said that on Monday night, prosecution said it received the records of their arrest and that they are being held inside two central security forces camps.

Sunday marked the fourth anniversary of the January 2011 uprising. The anniversary was marred by violence which left at least 23 dead. More than 500 were arrested in the aftermath.

Earlier on Tuesday, prosecution ordered the detention of 90 people arrested during the deadly violence.

Human Rights Watch said there is a need in Egypt "for an independent investigation into the authorities’ excessive use of force," in a statement on Monday.   

The violence in Egypt was condemned by the United States, United Kingdom and most recently, the United Nations. Egypt's Foreign Ministry responded to the condemnations with criticism.