Authorities in Bahrain have ordered an investigation into the "beating and death" of an inmate in custody in Jaw Prison, the state's interior ministry has said.
The ministry refrained from revealing the name of the inmate in their statement on Saturday, but activists from a Shia group identified the individual as Hassan al-Sheikh.
The group also said that al-Sheikh died because he was tortured while imprisoned.
The Interior Minister, Sheikh Rashid bin Abdullah al-Khalifa, has ordered an internal review after the prosecution's investigation into the death of a prisoner, the ministry's statement said.
The review will take a look into all procedures followed in prisons.
"The death of the man thought to have been at the hands of three ministry personnel was irresponsible, unjustified and unacceptable," al-Khalifa was quoted as saying, insisting the incident was an isolated event.
Hundreds of Shias have been arrested and faced trial after the month-long uprising in March 2011.
Shia protesters have regularly clashed with security forces in villages outside the Bahraini capital, Manama.