Belgian prosecutors on Wednesday said they have detained four suspected Islamic State (ISIS) group recruiters, who they say may have planned new attacks in the country, The Associated Press reports.

The Federal Prosecutor’s Office said in a statement that all four were charged with participating in the activities of a terrorist group.

Two were ordered arrested by an investigating judge, one was released under strict conditions and one was released with an electronic bracelet, according to AP.

The statement stressed, however, that the four do not appear to have links to the suicide bombers who struck the Brussels Airport and subway on March 22, killing 32 people.

Prosecutors said initial findings of the investigation indicated there may also have been plans for attacks in Belgium, but provided no details.

A Brussels court recently handed jail terms of up to seven years to 26 members of a group that recruited fighters for Syria and had included one of the suicide bombers responsible for the March 22 attacks.

The trial concerned suspected jihadists who left Belgium for Syria between 2012 and 2014. The accused were seen as participating in the activities of a terrorist group to varying degrees.