NEW DELHI: A massive manhunt is underway for surviving members and accomplices of the group that killed over a 129 people in Paris on Friday night. Meanwhile, France has begun bombing Islamic State strongholds in Raqqa, Syria, in an indication that the reaction to the attack is going to be an increased military response.

France has launched an international manhunt for Brussels-born Salah Abdeslam, 26, believed to be a key suspect. Abdeslam was initially stopped by officers following the attacks in Paris, but let go. Police have searched and carried out raids in a Paris suburb, Bobigny, with major operations also taking place in Jeumont, close to the French border with Belgium, and in the southern city of Grenoble.

Abdeslam is believed to have rented a VW Polo car that was found near the Bataclan concert hall, where 89 people died. On Saturday, he was stopped by police near the Belgian border and questioned, but let go, along with two other men who were in the car with him.

French news channel BFMTV quoted an investigation source as saying that Abdeslam and one of the other attackers were known to the Belgian authorities. Abdeslam is one of three Belgian brothers believed to be involved in Friday’s attacks, with the other two being Brahim Abdeslam, 31 -- who blew himself up outside a bar on the Boulevard Voltaire near the Bataclan, and Mohammed -- who was picked up from the Brussels neighbourhood of Molenbeek while returning from Paris and remains in custody.

Brussels police say they have made a total of seven arrests in connection with the Paris attacks.

The brothers were traced over the rental of VW Polo and one other car, a Seat containing Kalashnikov automatic rifles that was found abandoned in the Paris suburb of Montreuil.

A fourth attacker is believed to have Belgian roots. Bilal Hadfi, who was aged about 20, was one of three attackers who died at the Stade de France after detonating suicide belts. BFMTV said he lived in Brussels and was known to the authorities.

Bernard Cazeneuve, French Interior Minister, said the attacks in Paris had been prepared "by a group of individuals based in Belgium" who had "benefited from accomplices in France". Belgium's Premier Charles Michel vowed to crack down on Molenbeek, saying, "I have noticed there is almost always a link to Molenbeek, that there is a gigantic problem there.”

One of the attackers, has been identified is 29-year-old Frenchman Omar Ismail Mostefai. Mostefai also blew himself up at the Bataclan. He was being watched by the French authorities for potential radicalisation and had a criminal record.

Authorities also found a Syrian passport at the site of the Stade de France suicide bombing, in the name of a man who arrived as a refugee in Greece before claiming asylum in Serbia. It is not known whether the man named in the passport had a definite link to the attacks, as Syrian passports are hot currency at border crossings.

Meanwhile, France bombed the Syrian city of Raqqa on Sunday night, following meetings where President François Hollande vowed to be “unforgiving with the barbarians” of the Islamic State after the carnage in Paris.

The attack on Raqqa is France’s most aggressive intervention in Syria yet, as although France has been bombing Islamic State strongholds in Iraq, its presence in Syria has thus far been limited as it has been cautious of strengthening the hand of President Bashar al-Assad by killing his enemies.