Confusion reigned Tuesday over the fate of the brother-in-law of a notorious jihadist whose 2012 killing spree shocked France, after the interior ministry said he had been arrested at a Paris airport but police and his lawyers later denied this.

The man -- who is married to the sister of Mohamed Merah, an Al Qaeda-inspired gunman who shot dead seven people in the southwestern city of Toulouse in March 2012 -- was thought to have been arrested in Turkey along with two others on suspicion of being part of a network that recruited jihadists for Syria.

On Tuesday afternoon, a source at France's interior ministry said the three suspects had been arrested at a Paris airport after Turkey handed them over to French authorities.

But a police source and an airport source later denied this, saying they had never arrived in France.

The airport source said the plane they were due to be on "was stopped on the tarmac" at Orly airport near Paris but the three suspects "were not inside," adding that the captain had refused to accept them on the flight after Turkish police failed to provide adequate documents.

Adding to the confusion, the lawyers for the three men told AFP they had actually returned to France on Tuesday, but had not been arrested.

Pierre Dunac and Apollinaire Legros-Gimbert said the three had been unable to board a flight from Turkey to Paris as planned but later took another plane to an airport somewhere else in France.

The interior ministry, meanwhile, remained silent on the affair mid-evening.

French authorities are wary about nationals who have travelled to Syria and Iraq -- where the radical Islamic State group occupies large areas -- and may return to their home country to stage attacks.

Already in May, Interior Minister Bernard Cazeneuve had warned that Souad Merah, the sister of the gunman who killed three French soldiers and four civilians -- including three children -- who were Jewish in 2012 in Toulouse, had left France and may be fighting in Syria.

Mohamed Merah himself died after being shot by police following a prolonged stand-off at the apartment block where he lived.

It later emerged that he had visited Pakistan and Afghanistan prior to his attacks and had been on the radar of French intelligence, who had gravely underestimated the threat he posed.

His sister Souad left Toulouse in May for Barcelona, from where she took a flight to Istanbul and then another plane for the Turkish city of Gaziantep, near the Syrian border.

According to a source close to the case, she is currently in Algeria after having left Syria.

According to Cazeneuve, around 930 French citizens or residents, including at least 60 women, are either actively engaged in jihad in Iraq and Syria or are planning to go.

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