The Department said the decision comes following the detection of a COVID-19 patient among the inmates at the Welikada prison.
Over 170 persons have been identified as having come into direct contact with the infected inmate.
More than 300 PCR tests have been conducted on inmates and prison guards at the Welikada prison so far.
The inmate at the Welikada prison had been detected with the coronavirus after being transferred from the Kandakadu Rehabilitation Center on 27 June.
A quarantine process was later implemented at the Welikada prison. (Colombo Gazette)