The Dongbu Detention Center in eastern Seoul reported 288 new cases of the coronavirus in its second mass outbreak, bringing the total number of infections linked to the facility nationwide to 514, the justice ministry said Friday.

In its second mass testing on Wednesday, the prison found 286 cases among prisoners and two infected staff members, according to the ministry.

A total of 2,021 prisoners and 416 staff members took part in the tests. Former President Lee Myung-bak, who has been serving his prison sentence there on corruption charges, was not among those tested because he has been hospitalized for an underlying disease.

Lee tested negative during the prison's first mass testing on Dec. 18, which produced 187 positive results.

According to the Central Disease Control Headquarters (CDCH), 15 buildings at the detention center have been placed under cohort isolation and additional medical staff have been sent to treat the patients.

For moderate and serious cases of COVID-19, prison authorities are sending the patients to hospitals for treatment and requesting a suspension of their sentences.

The CDCH said it is in talks with the ministry over sending the patients to a newly built prison building or a government-designated residential treatment center.

Starting Wednesday, all new inmates have been placed under three-week quarantine, instead of two, and are being tested for COVID-19 at the beginning and end of their quarantine periods.

At the Seoul Detention Center, just south of Seoul, no new coronavirus cases have been reported so far after Tuesday's mass testing of 3,221 inmates and staff.

The facility previously reported two cases.

Former President Park Geun-hye, who is incarcerated there, tested negative. (Yonhap)