A new report from Belgian media alleges that Islamic State fighters who left Syria to travel through illegal migrant routes are planning on attacking targets in Belgium and France.

The Belgian anti-terrorist agency has sent a new warning to police across Belgium and France saying that Islamic State fighters have left Syria around a week and a half ago to reach Europe via Turkey and Greece.

The fighters are said to have travelled by boat without any identifying documents or passports. The Islamic State members have since separated into two groups, one set for Belgium and the other for France. According to Belgian paper La Derniere Heure, who intercepted the communication, the terrorists are in possession of weapons and their actions may well be imminent.

The attacks in the Belgian capital would likely be targeting shopping centres, restaurants, an unnamed American fast food chain, and potentially law enforcement targets, similar to that experienced recently in France when a police officer and his wife were stabbed to death in Paris.

The Belgian anti-terrorist organisation Coordination Body for Threat Analysis (OCAM) has raised their terror threat level to “3 serious”, and in coordination with the Crisis Centre in Belgium consider a real possibility of terror attacks in Brussels. OCAM says they are considering postponing or even cancelling major events in the Belgian capital due to the severity of the threat.

OCAM claimed that part of the reason for the heightened alert is because they have not yet located the explosives and weapons cache used by the March 22nd Brussels bombers.

“There are sleeper cells of the Islamic State in Europe,” they stated, adding that they are not able to exclude the possibility that the terror cells coming from Syria will not target Belgian infrastructure including nuclear power plants. Earlier this year the government announced plans to hand out iodine tablets to civilians in the case of an impending nuclear disaster.

“We believe the threat is high or very high,” they said, and noted that the severity comes from the potential number of victims or infrastructure that could be broadly effected in a terror attack.

Director of OCAM Paul Van Tigchelt attempted to put some perspective and clarification on the leaked warning saying:

“OCAM receives all kinds of information. It is most often raw information,” clarifying that “our mission, in conjunction with our partners, is to contextualise, analyse and verify their reliability. Based on this exercise, we concluded that with respect to this information, there was yet no need to increase the level of threat against targets that are mentioned.”

There has been some criticism over the methodology of the Belgian security services when it comes to dealing with terror threat information. Critics said that Belgian authorities refused to take seriously information that may have led to the arrest of one of the Paris attackers last year.

Authorities were also embarrassed after reports came out that the Brussels airport which was subject to attack in March was revealed to employ over 50 known Salafist radicals.