Police stormed an apartment building after intelligence that the suspected ringleader of the Paris attacks was holed up inside - his fate is so far unknown - but who is Abdelhamid Abaaoud?

The 27-year-old is thought to be from the Molenbeek area of Brussels, also home to other members of the terror cell that carried out the massacre.

He is reported to have had links to thwarted attacks on a Paris-bound train - when two US soldiers and a civilian overpowered a gunman - and a separate plot to attack a church.

He is also believed to have organised and financed a terror cell in the Belgian city of Verviers.

Two of his suspected accomplices were killed in a counter-terrorism raid in the city in January, after which he boasted of being able to easily escape and travel to Syria.

Abaaoud, who also uses the name Abu Omar al Baljiki, is of Moroccan origin.

In February, Islamic State's online magazine, Dabiq, carried an interview with an Islamist with that name who said he had travelled through Europe to organise attacks and procure weapons.

He said he wanted to "terrorise the crusaders waging war against the Muslims".

Abaaoud claimed a police officer had stopped him and let him go in the wake of the Verviers raid - even after his image had been released in the media.

He said in the interview: "I was even stopped by an officer who contemplated me so as to compare me to the picture, but he let me go, as he did not see the resemblance! ...

"All this proves that a Muslim should not fear the bloated image of the crusader intelligence.

"My name and picture were all over the news yet I was able to stay in their homeland, plan operations against them, and leave safely [to Syria] when doing so became necessary."

Abaaoud was also named in various media last year as the elder brother of 13-year-old Younes Abaaoud, who left Belgium to become a child-fighter in Syria.

It is thought Abaaoud, who was once a student at one of Brussels' most prestigious high schools, Saint Pierre d'Uccle, encouraged his sibling to join him in the war-ravaged country.

"All my life, I have seen the blood of Muslims flow," he said in a video made public last year.

"I pray that Allah will break the backs of those who oppose him, his soldiers and his admirers, and that he will exterminate them."

Independent journalists Etienne Huver and Guillaume Lhotellier, working on the Turkish-Syrian border, last year obtained photos and a video of him with his friends loading a truck with blooded corpses.

A smiling Abaaoud tells the camera: "Before we towed jet skis, motorcycles, quad bikes, big trailers filled with gifts for vacation in Morocco.

"Now, thank God, following God's path, we're towing apostates, infidels who are fighting us."

Huver told Associated Press that Abaaoud was giving orders and seemed to be a "charismatic guy who's going up in the world".

"You can see a combatant who's ready to climb the ranks," said the journalist.