France has launched a counter propaganda attack against the Islamic State (Isis) terror group, with a video aimed at dissuading young French Muslims to join the jihad in the Middle East.

Three weeks after the deadly Islamist attacks in Paris, the French government has released a short online clip entitled They Tell You... being promoted under the hashtag #Stopdjihadisme, which takes aim at IS's online recruitment strategy.

The 1:56 long video juxtaposes footage released by the IS propaganda machine, glorifying jihadism, with images of death and brutality inside the self-styled caliphate.

"They tell you: 'Sacrifice yourself with us, you'll defend a right cause'. In reality you'll find hell on earth and you'll die alone, far from home," the video says, showing some of IS's many summary executions.

The clip also addresses Muslim women at risk of becoming jihadi brides, warning them about the dire life conditions in war-torn Syria.

"They tell you: 'Come start a family with one of our heroes'. In reality, you'll raise your children amid war and terror," the video says.

More than 1,200 Frenchmen are believed to be fighting in Iraq and Syria, making the European country the largest western contributor of militants to Islamist organisations there, according to the International Centre for the Study of Radicalisation (ICSR).

France has tightened security in the wake of the attacks that left 20 people, including three Islamist gunmen, dead in Paris.

Earlier this week, anti-terror police arrested several alleged jihadists in Lunel, a small southern town that has grown a dubious reputation as a recruitment hotspot for Islamic fundamentalists.