Belgian police suspect that the four people they arrested on Wednesday in northern Belgium were recruiting for the Islamic State (IS), and plotting terror attacks in the country.
"We found traces of plans for an attack in Belgium," Eric Van der Sypt, a spokesman for the Belgium's federal prosecutor, told AFP.
According to French daily Le Monde, some of the attacks were to be carried out in the north of the country. Belgian public broadcaster RTBF said that one of the targets was the train station in the northern city of Antwerp.
The individuals were arrested during police searches in Ternat, Borgerhout and Antwerp. In a statement released after the arrests, officials said that they had found no weapons or explosives during the search, and that the investigation was not linked to the March 22 airport and subway suicide attacks in Brussels.
The prosecutor's office also stated that the four suspects were planning to recruit individuals to join the ranks of IS in Syria or Libya. Some of the individuals had planned to travel to those regions themselves to wage Jihad.
RTBF has reported that the suspects were in contact with IS executioner Hicham Chaib, who was close to Fouad Belkacem, the former leader of Sharia4Belgium, a group that was accused of running a jihadist recruitment cell in Belgium. Belkacem was sentenced to 12 years in prison in 2015 for his role in the organization.
In an IS propaganda video released after the Brussels attacks, Chaib praised the suicide bombings and warned of more attacks.
According to French daily Libération, one suspect has been formally placed under arrest, while another has been ordered to wear an electronic monitoring device. The two remaining suspects have been released under judicial supervision. All four have been charged with terror-related offenses.