AFP - New terrorism charges were expected Monday in the case of dozens of Somali-Americans, who disappeared from their homes in Minnesota and are believed to have joined an Islamist militia in Somalia.

A spokeswoman for the Department of Justice confirmed that a host of documents related to the case would be unsealed at an afternoon press conference but declined to release any further information.

Officials are worried that recruiting efforts among the Somali-Americans living in the Minneapolis, Minnesota have created a "jihadi pipeline" funneling youth to the battlefields of Somalia, National Public Radio reported.

One agent told the radio network that the year-long investigation is one of the biggest domestic terrorism cases the Federal Bureau of Investigation has engaged in since the terrorist attacks of September 11, 2001.

At least two dozen youths -- all of whom were doing well in school and being raised by single mothers -- have gone to Somalia to join the fighting in a bitter civil war since 2007, NPR reported.

Five of them have been killed there.

Citing people close to the investigation, NPR reported that people loosely linked to the Al-Qaeda inspired Islamist group al-Shabab "had taken it upon themselves to radicalize, recruit, and send young men from the Somali community in the Twin Cities to Somalia to fight for the group."

Six people have already faced terrorism charges related to the investigation in recent months and charges against eight more were set to be unsealed on Monday, NPR reported.