A chartered plane carrying some 300 South Koreans detained in a recent U.S. immigration raid is likely to depart from an airport in Atlanta around noon on Thursday.

According to a source familiar with the matter, the detainees will be released from the U.S. Immigration and Customs Enforcement's detention facility in Folkston, Georgia, between 2 a.m. and 4 a.m. Thursday.

They will then board buses to make the 430-kilometer trip to Hartsfield-Jackson Atlanta International Airport, a drive that typically takes four and a half hours.

Upon their arrival at the airport, the detainees will immediately board a Korean Air charter flight that has been on standby at the airport since Wednesday morning.

The plane was initially scheduled to depart from Atlanta at around 2:30 p.m. Wednesday, local time, but was delayed as the release of the detainees was postponed due to issues on the U.S. side.