PARIS/GENEVA (Reuters) - Switzerland is sending a Tunisian couple who include the brother of a man presumed to have killed two people in a knife attack at a French train station back to their home country for security reasons, Swiss federal police said on Tuesday.

The couple were arrested in the Swiss town of Chiasso near the Swiss-Italian border on Sunday night where they sought asylum. They will detained pending their expulsion, Swiss federal police said, giving no date.

“The man is known to foreign police services for his links with the jihadist terrorist movement. For now his role in the Marseille attack, if any, is not clear,” Swiss federal police said in a statement giving no names or ages for the couple.

Earlier a source close to the investigation said on Tuesday

that Swiss had detained two Tunisians wanted in connection with a deadly knife attack at Marseille train station on Oct. 1.

Swiss police confirmed that one of the two detained is a brother of 29-year-old Ahmed Hannachi, who was shot dead by a French soldier after killing two young women outside the station in southern France.

Authorities are investigating the attack as a “probable” terrorist act.

Hannachi’s younger brother, Anis, was arrested in Italy earlier this month.

More than 240 people have been killed in France since 2015 in attacks by assailants who pledged allegiance to, or said they were inspired by, the Islamic State group.

Earlier this month, the French parliament adopted counter-terrorism legislation to increase police surveillance powers and make it easier to close mosques suspected of preaching hatred - a law which civil rights groups said would infringe on personal freedoms.