Paris authorities have released a picture of a man they said was the third suicide bomber at the Stade de France, in a call for witnesses as they try to identify him.

Of those three stadium attackers, police have so far identified one man by name.

It comes as investigators extended into a fifth day the detention of a man arrested on Wednesday outside the building where the suspected ringleader of the Paris attacks died, the prosecutor's office said.

Jawad Bendaoud told a French television station he had been asked to put two people up in his apartment for three days, but had no idea they had anything to do with terrorism. He was then taken away by police.

Under an anti-terrorism law introduced in 2006, terrorism suspects can be held for up to six days if there is a serious risk of an imminent act of terrorism, or for international cooperation. Then they must be charged or released.