Forensic experts are trying to determine whether a body recovered following a dramatic police shoot-out in Paris is that of the mastermind behind last week's atrocities in the French capital.
Authorities say a second attack was foiled when Swat teams laid siege to a flat in the northern suburb of Saint-Denis for seven hours in a major pre-dawn raid on Wednesday.
A woman suicide bomber blew herself up and another person died following the gunfight, while eight people were arrested.
Paris prosecutor Francois Molins said the detained suspects did not include 27-year-old Abdelhamid Abaaoud, the Belgian jihadist believed to be the ringleader of last Friday's massacres which left 129 dead.
Two European sources told the Washington Post that Abaaoud was killed during the police operation, but officials have not yet been able to identify the bodies due to their condition, Mr Molins said.
It remains unclear whether the suspected mastermind of last week's attacks has been killed or is still at large, the French Interior Ministry and Paris prosecutor's office said.
Belgian authorities today launched six raids in the Brussels region linked to Bilal Hadfi, one of the suicide bombers in Friday's attacks.
Meanwhile, French Prime Minister Manuel Valls warned terrorists could use chemical or biological weapons, and urged an extension of France's state of emergency.
Mr Molins said the operation on Wednesday had neutralised a "new terrorist threat", and that "everything led us to believe that, considering their armaments, the structured organisation and their determination, they were ready to act".
The jihadis were set to carry out a second attack targeting Charles de Gaulle airport and the city's financial district La Defense, according to reports.
Salah Abdeslam, one of the suspected gunmen who is now the focus of an international manhunt, was not among those arrested, the prosecutor added.
Belgian police are also reportedly searching for a man named Mohamed K, from Roubaix, northern France, who is suspected of supplying the terrorist gang with explosives.
Belgian Prime Minister Charles Michel has pledged 400 million euros (£280 million) for a package of additional anti-terror measures in the wake of the attacks in Paris.
Wednesday's raid was launched after a discarded mobile phone and tapped telephone conversations allowed investigators to identify a series of safe houses, with the suggestion that Abaaoud may have been holed up in an apartment less than a mile from the Stade de France, where one of the terror attacks took place.
Police fired about 5,000 rounds of ammunition during an early-morning exchange of gunfire which lasted about an hour as the terrorist cell barricaded themselves in the hideout.
Heavily armed police squads were initiallythwarted by an armoured door and had to use assault guns, sniper rifles, grenades and explosives during the "extremely difficult" and "complex" operation.
Two bodies were found in the rubble of the building after an explosion thought to have been caused when a woman, named in reports as Abaaoud's cousin Hasna Aitboulachen, detonated a suicide vest.
Mr Molins said: "At least one terrorist killed herself with an explosive. The floor of the flat collapsed and the state of the bodies and what is left of them will demand some more investigation."
He added: "I'm not in a position to give a precise and definitive number for the people who died, nor their identities, but there are at least two dead people."
Two men were found inside the flat, one of whom was injured and arrested. The eight arrested included one woman and a man whose flat was used as a hideout by the terror cell and are being interrogated.
Mr Molins said: "The identities of the people who were arrested in this building are not absolutely certain but Abaaoud and Salah Abdeslam are not part of the people who have been arrested."
Several police officers were slightly injured during the raid and a police dog named Diesel was also killed.