French Prime Minister Manuel Valls (2nd L) and French Interior Minister Bernard Cazeneuve (R) walk out of the first house liberated in 1944 in Benouville, northwestern France, on May 16, 2014.
The sister of Al Qaeda inspired gunman Mohamed Merah who killed seven people in and around Toulouse has left France and could be fighting in Syria, Interior Minister Bernard Cazeneuve said on Friday.
French authorities lost track of 35-year-old Souad Merah in March when a school at which one of her children was studying alerted them that the pupil had failed to turn up for several days.
"There is a strong suspicion that she is in Syria," Cazeneuve told Europe1 radio.
Souad Merah, who has four children aged between nine months and 14 years, left Toulouse at the start of May for Barcelona in Spain, according to French sources investigating the case.
She was accompanied by her children.
Cazeneuve said she took a flight for Istanbul from Barcelona on May 9 and took another plane the same day for the Turkish city of Gaziantep, which is near the Syrian border.
Souad Merah had been 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 March 2012.
Mohammed Merah died after being shot by police following a prolonged stand-off at the apartment block where he lived.
Since then it has emerged that he had visited Pakistan and Afghanistan prior to his attacks and had been on the radar of French intelligence, who had gravely under-estimated the threat he posed.
Cazeneuve said earlier this month that 285 French citizens were currently fighting in Syria, despite a slew of measures to prevent people from travelling to the war-torn country.
There have been mounting concerns in France over the number of young jihadists heading to fight in Syria, with authorities fearing they could pose a major security threat if they return home as battle-hardened veterans.
The French government unveiled an anti-terrorism plan in April to prevent the radicalisation of nationals, thwart online recruitment and make it more difficult for aspiring jihadists to leave the country for Syria.