Swiss police have detained two Tunisians wanted in connection with a deadly knife attack at Marseille train station in France on Oct. 1, a source close to the investigation said on Tuesday.
Swiss police confirmed that one of the two detained men is a brother of the knifeman, 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.
Swiss federal police said the brother of Hannachi they had detained was known to foreign police forces for links with the "jihadist terrorist movement," though it was unclear what role, if any, the suspect played in the Marseille attack.
The two were detained in Chiasso near the Swiss-Italian border on Sunday evening, Swiss police said, without giving their names or ages.
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.