Authorities 'ignored links' between Paris attack ringleader and IS

Facebook activities showing the notorious black and white flag linked to the militant group was picked up by authorities three weeks before the November attacks but were later ignored by security officials, a leaked parliamentary report revealed.

But without giving much detail, broadcaster RTBF, who initially reported the revelations, later said police determined the Facebook profile did not belong to the suspected ringleader, Salah Abdeslam.

Information within the clandestine report is allegedly based on interviews by lawmakers with senior officials and police and outlines a series of failures ahead of the attacks that left 130 people dead in Paris.

The revelation is the latest in a list of alleged failures by Belgian police in the months leading up to the attacks.

Authorities also knew Abdeslam was in contact with the suspected ringleader Abdelhamid Abaaoud – an influential member of the Islamic State group – in early 2015.

A probe into Abdeslam and his brother Brahim – who was detonated himself in a Paris café during the attacks – was dropped by police six months prior to the incident.

Salah Abdeslam was shot and arrested in Brussels on March 18 after four months on the run as Europe's most wanted man.

He was found to have links with a cell of militants that conducted the bomb attacks in Brussels on March 22, four days after his arrest.

Abdeslam was recently extradited to France where he is currently awaiting trial for his alleged role in the killings.