LOS ANGELES—Officials don’t know when they will reopen a troubled immigrant detention center that was closed for preventive maintenance and forced the transfer of hundreds of detainees to other facilities.

Immigration and Customs Enforcement officials closed the center Oct. 22, saying the repair work would take at least a month. But they now say they don’t know when the center will be reopened and are still assessing the repairs to the sprinkler and hot water systems.

The center, located in the San Pedro area of Los Angeles, housed more than 400 immigrants who were detained by authorities and face deportation. The detainees were moved to other sites in California, Texas, Arizona and Washington.

Last week, ICE declined to discuss the future of the center, issuing a statement saying: “At this time, ICE is working with engineering and construction professionals to evaluate the extent of the work to be done.”

Meanwhile, immigration judges have approved the government’s requests to move the vast majority of the 299 pending cases from San Pedro to other courts around the nation. But immigration advocates say the transfers have added to the delays.

The detention center is one of several nationwide to come under scrutiny from immigrant and civil rights groups.

Last summer, a transgender Mexican immigrant with AIDS being housed there died while in custody. The family claimed the immigrant was improperly denied medical attention, a contention officials rejected.