The Al Wefaq opposition party says over 90 children are languishing behind bars in the Al Khalifa prisons.
Bahrain’s main opposition bloc also accuses the regime of bringing false charges against the minors, treating them like adult inmates, abusing their rights and even torturing them while in detention.
The comments come after Al Wefaq announced three days of mourning following the death of a teenager at the hands of regime forces.
Saudi-backed Bahraini forces beat to death Husam al-Haddad, the latest victim of police brutality, when they carried out an attack on a peaceful demonstration in the city of Muharraq, northwest of Manama, on August 17.
Several anti-regime protests have been held across the country to condemn the killing of Haddad.
Bahraini protesters have been holding demonstrations against the ruling Al Khalifa family since February 2011 and they hold King Hamad bin Isa Al Khalifa responsible for the deaths of the demonstrators throughout the uprising.
Bahrain hosts the US Fifth Fleet and is among the Persian Gulf countries such as Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates that receive military equipment from the United States.