The ringleader of the Paris attacks was drinking beer and smoking cannabis after the massacres, a witness has exclusively told Sky News.

French counter-terror police swooped on a flat in the northern suburb of Saint Denis on Wednesday morning and have now confirmed that Europe's most wanted Abdelhamid Abaaoud was killed in the seven hour siege .

Estate agent Amel told Sky News that she is convinced she saw the prime suspect outside the flats over the weekend after the attacks across Paris, which killed 129 people.

"I saw him in Muslim dress, down at the building with all these guys, perhaps eight or 10 of them," she said.

"That is a street I go in every day ... we said 'hello' to everyone in the group, every day they were sitting there but I noticed him because he was wearing Islamic dress with the hat ... the others were in normal clothes they always are.

"Afterwards we saw the TV and my sister said to me: 'Isn't that the guy we saw the other day?'

"I am 99.9% sure it was him, it is crazy.

"They were there like smoking joints and drinking beers - they are often in the street so I know them, I know them."

The 28-year-old Belgian may also have been involved in four of six thwarted attacks in France this year, including an assault by a gunman on a high-speed train which was thwarted by three Americans.

He was wanted on international warrants and had been sentenced in his absence in Belgium to 20 years in prison.

On Wednesday morning, Amel watched from her mother's flat as the siege in which Abaaoud was killed played out on the streets below.

"It was like in front of my window, it is like a movie, like an American movie for me. I cannot believe he was just here.

"I'm so happy he died ... I understand he was the head of all these operations so I am really happy and I hope they kill them all."

Salah Abdeslam, one of the suspected gunmen in the attacks, is still being hunted by police.

French Prime Minister Manuel Valls said on Thursday that it was not clear whether Abdeslam was in France or Belgium, or if there were any more cells directly linked to the Paris atttackers still at large.

"The threat is there. We don't know at this point in the investigation if there are groups, individuals, who are directly linked to the attack on Friday evening, in Paris, in Saint Denis," he told France 2 television.