An object believed to be an explosive belt was found this afternoon in a town south of Paris, near where a phone used by suspected assailant Salah Abdeslamw as detected on the night of the attacks, a source close to the investigation said.
Abdeslam, whose brother blew himself up in the Paris attacks, has been on the run since the assault that killed 130 people in the French capital on 13 November and is the focus of a massive manhunt.
French investigators initially believed Abdeslam had been in a black Seat Leon car that was used in the shootings at restaurants and cafés in the 10th and 11th districts of the capital.
A source close to the investigation said, however, that Abdeslam's mobile phone was detected after the attacks in the northern 18th district of Paris, near an abandoned Renault Clio car that Abdeslam had rented.
The source said there was now a "strong suspicion" he had been driving the Clio rather than being in the Seat.
Furthermore, when the so-called Islamic State militant claimed responsibility for the attacks, it said it had targeted the Stade de France soccer stadium, the Bataclan concert hall, the 10th and 11th districts, and the 18th district.
Since there were no explosions or shootings in the 18th, investigators are now wondering whether there was a failed, or aborted, attack, the source said.
Abdeslam's phone was detected later on 13 November by a mobile phone mast in Chatillon in the south of Paris, near Montrouge where the suspected explosive belt was dumped.
But the source said it was too soon to say whether the object had been in contact with Abdeslam.
"The thesis that he abandoned [the attack] is just coming from people who brought him back [to Belgium]. But we don't know why. Maybe he had a technical problem with his explosive belt, for example," said a police source.
As authorities tried to establish Abdeslam's movements and whereabouts, a source said he travelled through Italy in August with a companion, but his presence caused no alarm because he was not a wanted man at the time.
His companion was Ahmet Dahmani, a Belgian man of Moroccan origin who was arrested in Turkey last week on suspicion of involvement in the Paris attacks, the investigative source said.
In Belgium, prosecutors said they had charged a fourth person with terrorist offences linked to the Paris attacks.
They released all 15 others detained in police raids yesterday.
Air strikes
Meanwhile, French jets from the Charles de Gaulle aircraft carrier struck Islamic State targets in Iraq today while Britain offered France the use of an air base in Cyprus to hit the militants behind the Paris attacks.
French President Francois Hollande met British Prime Minister David Cameron in Paris as part of efforts to rally support for the fight against Islamic State, which claimed the 13 November attacks.
Mr Hollande is also due to visit the US and Russia this week.
Mr Cameron offered air-to-air refuelling services and said he was convinced Britain should carry out air strikes alongside France and would be recommending that Britain's parliament vote through such measures.
France has intensified its bombings in Syria since the attacks in Paris.
French jets taking off from the country's flagship in the eastern Mediterranean destroyed targets in Ramadi and Mosul in Iraq today in support of Iraqi forces on the ground, the French armed forces said in a statement.
