Paris, Sep 23 (IANS): French police Tuesday arrested three men at Paris' Orly airport, suspected of joining Syrian insurgents in 2013, media reported.

The three suspects, among them the brother-in-law of Mohamed Merah who killed seven people in southern France in 2012, have been placed under custody, Xinhua reported citing news channel BFMTV.

According to the report, the suspects joined Syrian rebels in April 2013 and were arrested by Turkish authorities at the end of August on their way back home.

The French interior ministry's data showed more than 900 French nationals and residents joined combat in Syria, among whom 36 have been killed and 118 others returned home.

Under its anti-jihadi plan, France said it would ban travel to conflict zones where nationals could join fighters and monitor those who returned home after staying in Syria.

In the meantime, to curb the alarming number of radicalised young French who joined fighters in Syria, the French government has pledged to boost cyber-security, stay in close contact with jihadists' families and deport immediately foreign nationals who are involved in jihad cells.