Mohammed Merah
Mohamed MerahReuters

The sister of Mohamed Merah, the gunman who killed seven people after targeting a Jewish school in Toulouse, has allegedly left France for war-torn Syria according to reports.

Authorities are said to have lost track of Souad Merah, 36, for several days and suspect she has slipped out of the south-eastern French city with her four children to join her new companion in Turkey from where they crossed into Syria.

The woman was taken into custody in April on suspicion that she blessed her brother Mohammed, 23, ahead of the killing spree in which he shot dead three French soldiers and four Jews - three children and a rabbi - in Tolouse and near the city in March 2012. Mohammed, who claimed he belonged to al-Qaida, was shot dead by police after a 32-hour stand-off at his flat.

Before the killing, Mohamed and his sister were considered by the French Central Directorate of Internal Intelligence (DCRI) as radical Salafist activists.

In December 2013, police interrogated Souad Merah in Paris after she was filmed by an undercover camera saying she was proud of Mohammed "for how he fought till the end". "The Jews are all about massacring the Muslims. I hate them. I think well of bin Laden. I told that to the cops. I am proud of my brother, proud, proud, proud," she said.

Souad later released a statement saying she condemned his brother's actions.

A Jewish group, the BNVCA, expressed "dismay" at the news that Souad had escaped police surveillance.

BNVCA's head, Sammy Ghozlan, called on police authorities ''to act quickly to find and imprison the radical dangerous Islamist who, like several hundred French citizens brainwashed into jihad, are trained to guerrilla and are likely to commit attacks, primarily targeting Jewish people, sites and schools in France".