The brother of Mohamed Merah, the Islamist gunman who claimed responsibility for killing seven people in the Toulouse area before being shot dead by police in a raid has told police investigators that he had no knowledge of his brother’s acts, but that he is “proud of them,” according to French media reports.

His brother, Abdelkader Merah, 29, was detained by police on Wednesday in connection with the Toulouse shootings, along with his wife, after they found explosives in his car. They then transferred him to Paris for questioning by anti-terrorism police.

Abdelkader Merah, described by police as a religious fundamentalist, is being investigated for possible links to Merah's attacks, which killed three children, a rabbi and three soldiers. In 2007, Abdelkader Merah was investigated for links to Iraqi
jihadists in 2007 but never charged.

Le Point news weekly and other French media reported him as telling investigators he had no knowledge of his brother's acts, but that he was "proud" of them.

Le Parisien newspaper reported that the elder Merah's phone was located near the site of the attack on a Jewish school Monday, and that the two brothers had dined together the night before.

Meanwhile, Merah's mother, Zoulikha Aziri, who was also detained on Wednesday, was released Friday evening. Her lawyer said she was devastated by a "sense of guilt and remorse" over her son's actions and did not dare return home for fear of reprisals.

It was not immediately clear whether Aziri would face any charges, Le Figaro reported.

Merah's uncle told Le Point magazine that his nephew had always been unstable but that "unstable" but that he could "never have imagined" him to be the so-called scooter killer.

"Religion has nothing to do with this. He got worked up all by himself," the brother of Merah's mother, whose identity was withheld, said.

Elsewhere in Toulouse, investigators said they had identified the Colt 45 pistol used by Merah in his three attacks. The gun was found in Merah's car, i-Tele channel reported.

Merah, a 23-year-old Frenchman of Algerian origin with a history of delinquency, told police he acted alone during his attacks between March 11 and March 19.

But questions are being asked as to how the jobless panelbeater, who claimed links to al-Qaida, managed to amass an expensive arsenal of assault weapons and pistols without external financial or logistical support.

Meanwhile, the government minister who oversaw the police investigation and raid slammed criticism of the operation as unfair and politically-motivated.

Interior Minister Claude Gueant told Le Figaro newspaper the criticisms, which came as campaigning resumed in the country's presidential elections, were "clearly inspired by political considerations" and were "out of place."

Several candidates have questioned why the police had failed to identify Merah as a suspect in the killing of three soldiers before he attacked a Jewish school on Monday.

Socialist candidate Francois Hollande also asked whether there was a serious lapse on the part of the intelligence services, who had questioned Merah in 2011 over trips to Afghanistan and Pakistan but had not kept him under constant surveillance since.

Security experts also questioned why the police did not try to overpower Merah by introducing gas into his apartment at the outset of the raid.

Gueant said the use of such a gas would have been illegal under international conventions.

Amaury de Hauteclocque, head of the elite police team that carried out the raid, told Le Figaro that Merah said he wanted to "join Allah and his 72 virgins" and that there was "no other solution in the end" but to kill him.

The French government on Saturday downgraded the terrorism alert level in the south-west of the country from "scarlet" following the killing by police Thursday of Mohamed Merah, Interior Minister Claude Gueant told AFP news agency.

The region around Toulouse had been placed on the highest alert level - a first for the country - following the killing of three children and a rabbi at a Jewish school on Monday.

Previously, all France had been on the second-highest threat level of "reinforced red."