Egyptian police are still holding five Eritrean refugees arrested during a demonstration in the capital, Cairo, on Sunday.
The refugees were protesting at the offices of the UN refugee agency (UNHCR) about delays in processing registrations for newly-arrived asylum seekers when police arrested more than 40 of them.
Most were released later the same day, but five were kept in different holding cells, report says.
One refugee following their cases told BBC Tigrinya that the police are trying to find out who organised the demonstration.
The London-based rights group the Eritrean Movement for Democracy and Human Rights said they fear the group could be deported back to Eritrea.
The UNHCR office in Egypt has not commented on the issue.