Weeks before the terrorist attacks in Paris last November, key suspect Salah Abdeslam had posted the flag of the Islamic State extremist group on social media but no action was taken, Belgian broadcaster RTBF reported Tuesday.
Abdeslam, a French national who had lived in Belgium, is believed to be the only surviving member of a group of terrorists who killed 130 people in a night of coordinated gun attacks and bombings at sites across Paris on November 13.
Following his arrest in Belgium in March, the 26-year-old has been transferred to French custody and charged with terrorist murder. His exact role in the Paris attacks is unknown.
Abdeslam had posted the Islamic State flag on social media three weeks before the attacks, RTBF reported. The country's threat analysis unit, OCAM, was aware of the fact, but neither the police nor intelligence services reacted, the broadcaster added.
Abdeslam and his brother Brahim - who blew himself up during the Paris attacks - had been interrogated by police in early 2015 because of suspicions that they wanted to travel to Syria, but were released at the time without charges.
Prosecutors had called for the brothers' telephone and email exchanges to be monitored, but this never occurred because of a lack of funding, according to the interim findings of a police monitoring body that were leaked to media last month.