PARIS (AFP) - Six French citizens have had their passports confiscated after allegedly planning to join extremist groups in Iraq and Syria and 40 more will soon join their ranks, France's Interior Minister Bernard Cazeneuve said Monday, marking the first time the counter-terrorism measure has been used.

"There are currently six administrative bans on leaving the country that have already been signed, and around 40 that are being prepared," Cazeneuve told reporters.

The right to remove passports was introduced as part of a raft of new counter-terrorism laws in November aimed at curbing the number of French citizens leaving to join extremist groups in the Middle East.

A security source said the six French who have been banned from travelling outside France were "imminently" about to travel to Syria.

Their passports and identity cards have been confiscated for six months, after which the order can be renewed.

Some 1,400 people living in France have either joined the extremist cause in Syria and Iraq or are planning to do so, Prime Minister Manuel Valls said last month.